U.S. patent number 5,493,427 [Application Number 08/247,995] was granted by the patent office on 1996-02-20 for three-dimensional display unit with a variable lens.
This patent grant is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Noritoshi Kako, Masayuki Katagiri, Toshio Nomura.
United States Patent |
5,493,427 |
Nomura , et al. |
February 20, 1996 |
Three-dimensional display unit with a variable lens
Abstract
A three-dimensional display unit has a liquid crystal panel for
simultaneously displaying a plurality of different parallax images
and an optical characteristic variable lens attached to the liquid
crystal panel. The optical characteristic variable lens is formed
by an array of cylindrical lenses such that a transparent substance
having high flexibility is supported by transparent electrodes from
both substance sides and optical characteristics of each of the
cylindrical lenses can be changed by applying a voltage to the
transparent substance to change at least one surface shape of the
transparent substance. The three-dimensional display unit may have
a head detecting section for detecting a spatial position of an
observer's head; and a control section connected to the head
detecting section and controlling an operation of the optical
characteristic variable lens based on position information of the
observer's head detected by the head detecting section such that a
stereoscopic image is regenerated in an optimum position of the
observer's head. Another three-dimensional display unit is also
shown.
Inventors: |
Nomura; Toshio (Yokkaichi,
JP), Katagiri; Masayuki (Soraku, JP), Kako;
Noritoshi (Chiba, JP) |
Assignee: |
Sharp Kabushiki Kaisha (Osaka,
JP)
|
Family
ID: |
27470901 |
Appl.
No.: |
08/247,995 |
Filed: |
May 23, 1994 |
Foreign Application Priority Data
|
|
|
|
|
May 25, 1993 [JP] |
|
|
5-122975 |
Sep 1, 1993 [JP] |
|
|
5-217372 |
Sep 1, 1993 [JP] |
|
|
5-217374 |
Sep 9, 1993 [JP] |
|
|
5-224349 |
|
Current U.S.
Class: |
349/5;
348/E13.072; 348/E13.014; 348/E13.028; 348/E13.022; 348/E13.015;
348/E13.049; 348/E13.046; 348/E13.033; 348/E13.044; 348/E13.03;
348/E13.043; 348/E13.059; 348/E13.029; 348/E13.052; 348/E13.05;
349/112; 349/15; 349/195; 348/59 |
Current CPC
Class: |
G02B
27/0093 (20130101); H04N 13/361 (20180501); H04N
13/305 (20180501); G02F 1/29 (20130101); H04N
13/368 (20180501); H04N 13/376 (20180501); H04N
13/31 (20180501); H04N 13/324 (20180501); H04N
13/349 (20180501); G02B 30/27 (20200101); H04N
13/398 (20180501); H04N 13/373 (20180501); H04N
13/38 (20180501); G02B 3/005 (20130101); H04N
13/307 (20180501); H04N 13/189 (20180501); H04N
13/286 (20180501); H04N 13/161 (20180501); G02F
2203/28 (20130101); H04N 13/239 (20180501); H04N
13/243 (20180501) |
Current International
Class: |
G02F
1/29 (20060101); G02B 3/00 (20060101); G02B
27/00 (20060101); G02B 27/22 (20060101); H04N
13/00 (20060101); G02F 001/1335 (); G02F 001/13 ();
G09G 003/36 () |
Field of
Search: |
;359/83,40,38,846,865,292,295,69 ;348/51,54,59 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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60-149294 |
|
Aug 1985 |
|
JP |
|
60-149295 |
|
Aug 1985 |
|
JP |
|
63-242093 |
|
Oct 1988 |
|
JP |
|
2-44995 |
|
Feb 1990 |
|
JP |
|
4-127122 |
|
Apr 1992 |
|
JP |
|
Other References
Isono et al., NHK Labs., "Autostereoscopic 3-D Display Using
LCD-Generated Active Barrier-Strip", Proceedings of the 22nd Image
Technology Conference, pp. 103-106, 1991..
|
Primary Examiner: Gross; Anita Pellman
Assistant Examiner: Miller; Charles
Attorney, Agent or Firm: Conlin; David G. Oliver; Milton
Claims
What is claimed is:
1. A three-dimensional display unit comprising:
a display means for simultaneously displaying a plurality of
different parallax images; and
an optical means attached to said display means and formed by an
array of cylindrical lenses such that a transparent substance
having high flexibility is supported by transparent electrodes from
both substance sides, and optical characteristics of each of said
cylindrical lenses can be changed by applying a voltage to said
transparent electrodes to change at least one surface shape of said
transparent substance.
2. A three-dimensional display unit as claimed in claim 1, wherein
said optical characteristics of each of said cylindrical lenses
include a focal length.
3. A three-dimensional display unit as claimed in claim 1, wherein
said display means includes a plurality of pixels each emitting a
light, non-penetrating portion, a masking means having an open
portion and an unopen portion receiving a part of said emitted
light and changing an optical path of said received part of said
emitted light, said masking means attached to a surface of said
display means and arranged at the same pitch as a pitch of the
respective pixels in accordance with said non-penetrating portion,
and said optical means is attached to a surface of said masking
means.
4. A three-dimensional display unit as claimed in claim 3, wherein
said unopen portion of the masking means has a light shielding film
for reducing the size of a non-display space corresponding to said
non-penetrating portion of said display means.
5. A three-dimensional display unit, as claimed in claim 1,
wherein
each of said cylindrical lenses has a vertical direction, and
said display means has a scanning means for scanning main scanning
lines thereof in the same direction as a longitudinal direction of
each of said cylindrical lenses, voltages applied to said main
scanning lines are reversed in polarity at every predetermined
number of said main scanning lines of the same frame and at the
same position in each respective frame.
6. A three-dimensional display unit, as claimed in claim 5,
wherein
said voltages applied to said main scanning lines are reversed in
polarity at every main scanning line of the same frame when the
number of different parallax images is an odd number.
7. A three-dimensional display unit comprising:
a display means for simultaneously displaying a plurality of
different parallax images;
an optical means attached to said display means and constructed by
an array of cylindrical lenses such that optical characteristics of
each of said cylindrical lenses can be changed;
a detecting means for detecting a spatial position of an observer's
head;
a control means connected to said detecting means and controlling
an operation of said optical means based on said detected spatial
position of the observer's head such that a stereoscopic image is
regenerated in an optimum position of the observer's head;
a plurality of stereoscopic signal sources for performing a
multiple-eye display; and
a selecting means connected to said stereoscopic signal sources and
said detecting means for selecting one of said stereoscopic signal
sources to display to said display means on the basis of said
detected spatial position of the observer's head.
8. A three-dimensional display unit, as claimed in claim 7, wherein
said optical means includes a liquid crystal.
9. A three-dimensional display unit as claimed in claim 7, wherein
a projecting lens and a diffusive layer are arranged between said
display means and said optical means.
10. A three-dimensional display unit, comprising:
a display means for simultaneously displaying a plurality of
different parallax images; and
an optical means, attached to the display means and formed by an
array of cylindrical lenses, such that a transparent substance is
supported by transparent electrodes from both substance sides, and
optical characteristics of each of the cylindrical lenses can be
changed by a voltage applied to said transparent electrodes to
provide a refractive index distribution of said transparent
substance,
wherein
said display means includes
a plurality of pixels, each emitting a light,
a non-penetrating portion,
a masking means having an open portion and an unopen portion
receiving a part of said emitted light and changing an optical path
of said received part of said emitted light, said masking means
being attached to a surface of said display means and arranged at
the same pitch as a pitch of the respective pixels in accordance
with said non-penetrating portion, and wherein
said optical means is attached to a surface of said masking
means.
11. A three-dimensional display unit, as claimed in claim 10,
wherein
said unopen portion of the masking means has a light-shielding film
for reducing the size of a non-display space, corresponding to said
non-penetrating portion of said display means.
12. A three-dimensional display unit, comprising:
a display means for simultaneously displaying a plurality of
different parallax images; and
an optical means, attached to the display means and formed by an
array of cylindrical lenses, such that a transparent substance is
supported by transparent electrodes from both substance sides, and
optical characteristics of each of the cylindrical lenses can be
changed, by a voltage applied to said transparent electrodes, to
provide a refractive index distribution of said transparent
substance,
wherein each of said cylindrical lenses has a vertical direction,
and said display means has a scanning means for scanning main
scanning lines thereof in the same direction as a longitudinal
direction of each of said cylindrical lenses, voltages applied to
said main scanning lines are reversed in polarity at every
predetermined number of said main scanning lines of the same frame
and at the same position of every frame.
13. A three-dimensional display unit, as claimed in claim 12,
wherein
said voltages applied to said main scanning lines are reversed in
polarity at every main scanning line of the same frame when the
number of different parallax images is an odd number.
14. A three-dimensional display unit, comprising:
a display means for simultaneously displaying a plurality of
different parallax images:
an optical means, attached to the display means and constructed by
an array of cylindrical lenses, such that optical characteristics
of each of the cylindrical lenses can be changed:
a detecting means for detecting a spatial position of an observer's
head; and
a control means, connected to said detecting means and controlling
an operation of said optical means, based on said spatial position,
of the observer's head, detected by said detecting means, such that
a stereoscopic image is regenerated in an optimum position of the
observer's head,
wherein said display means includes
a plurality of pixels each emitting a light,
a non-penetrating portion,
a masking means having an open portion and an unopen portion
receiving a part of said emitted light and changing an optical path
of said received part of said emitted light, said masking means
being attached to a surface of said display means and being
arranged at the same pitch as a pitch of the respective pixels in
accordance with said non-penetrating portion, and
wherein said optical means is attached to a surface of said masking
means.
15. A three-dimensional display unit, as claimed in claim 14,
wherein said unopen portion of the masking means has a
light-shielding film for reducing the size of a non-display space,
corresponding to said non-penetrating portion of said display
means.
16. A three-dimensional display unit, comprising:
a display means for simultaneously displaying a plurality of
different parallax images;
an optical means, attached to the display means and constructed by
an array of cylindrical lenses, such that optical characteristics
of each of the cylindrical lenses can be changed;
a detecting means for detecting a spatial position of an observer's
head; and
a control means, connected to said detecting means and controlling
an operation of said optical means, based on said spatial position,
of the observer's head, detected by said detecting means, such that
a stereoscopic image is regenerated in an optimum position of the
observer's head,
wherein each of said cylindrical lenses has a vertical direction,
and said display means has a scanning means for scanning main
scanning lines thereof in the same direction as a longitudinal
direction of each of said cylindrical lenses, voltages applied to
said main scanning lines are reversed in polarity at every
predetermined number of said main scanning lines of the same frame
and at the same position of every frame.
17. A three-dimensional display unit, as claimed in claim 16,
wherein said voltages applied to said main scanning lines are
reversed in polarity at every main scanning line of the same frame
when the number of different parallax images is an odd number.
18. A three-dimensional display unit, comprising:
a display means for simultaneously displaying a plurality of
different parallax images;
an optical means, attached to the display means and constructed by
an array of cylindrical lenses, such that optical characteristics
of each of the cylindrical lenses can be changed;
a detecting means for detecting a spatial position of an observer's
head; and
a control means, connected to said detecting means and controlling
an operation of said optical means, based on said spatial position,
of the observer's head, detected by said detecting means, such that
a stereoscopic image is regenerated in an optimum position of the
observer's head, and
further comprising a projecting lens and a diffusive layer,
arranged between said display means and said optical means.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a three-dimensional display unit
capable of regenerating a stereoscopic image without requiring any
special spectacles.
2. Description of the Related Art
In a general display technique, a three-dimensional display unit
using a lenticular lens is known as a device for displaying a
stereoscopic image without any spectacles. In particular, the
three-dimensional display unit is realized in combination with a
flat panel display such as a liquid crystal display since positions
of the lenticular lens and display pixels are easily aligned with
each other and a distance from a display face to the lenticular
lens is short.
FIG. 1 shows one general example of the three-dimensional display
unit of a direct viewing type in which the lenticular lens is
directly stuck to the display face of a liquid crystal panel. The
three-dimensional display unit shown in FIG. 1 is of a two-eye type
as an example.
One portion of a parallax image for a left-hand eye is displayed in
a pixel DD.sub.i1 of a liquid crystal panel 50. One portion of a
parallax image for a right-hand eye is displayed in a pixel
DD.sub.i2 of the liquid crystal panel 50. Index i is set to a value
from 1 to n.
Stereoscopic signal sources 52 and 53 are respective sources of
these parallax images. The parallax images are synthesized and
displayed by a stereoscopic signal synthesizer 54. A lenticular
lens 51 is arranged such that the lenticular lens 51 is closely
attached onto a front face of the liquid crystal panel 50. A
cylindrical lens LL.sub.i corresponds to a pair of pixels DD.sub.i1
and DD.sub.i2. Light is transmitted through the pixels DD.sub.i1
and DD.sub.i2 and is separated into light portions in display
spaces C and D in an observation region by a converging action of
the cylindrical lens LL.sub.i. An observer can observe a
stereoscopic image when left-hand and right-hand eyes of the
observer are respectively located in the spaces C and D.
In FIG. 1, the cylindrical lens LL.sub.i has the same lens shape,
but a pitch of the pair of pixels DD.sub.i1 and DD.sub.i2 is
different from that of the cylindrical lens LL.sub.i. In this case,
the pitch of the cylindrical lens is set to be slightly smaller
than the pitch of the pair of pixels DD.sub.i1 and DD.sub.i2.
Accordingly, a center of the pair of pixels is shifted from that of
the corresponding cylindrical lens in a peripheral portion of the
liquid crystal panel. An amount of this shift is increased as this
shift is caused in the peripheral portion. An incident angle of the
transmitted light from each of the pixels to the cylindrical lens
in a center of the liquid crystal panel 50 is different from that
in the peripheral portion of the liquid crystal panel 50 by this
shift. Accordingly, the transmitted light from pixels in the
peripheral portion of the liquid crystal panel 50 can be converged
into the specified spaces C and D in the observation region.
A three-dimensional display unit using a parallax barrier is known
as a device of another display type capable of observing a
stereoscopic image without any spectacles. FIG. 2 shows one general
example of the three-dimensional display unit in which this
parallax barrier is constructed by a liquid crystal panel.
The three-dimensional display unit shown in FIG. 2 is constructed
by two liquid crystal panels each having the same performance and
composed of a liquid crystal panel 61 for a display and a liquid
crystal panel 62 for a slit barrier. The three-dimensional display
unit shown in FIG. 2 is also constructed by a Fresnel lens 63
inserted between these liquid crystal panels 61 and 62, a personal
computer 64 for generating a three-dimensional image and a slit
barrier, etc. In this case, the two liquid crystal panels are
laminated with each other in a direction in which polarizing
directions of polarizing plates are in conformity with each other.
Further, the two liquid crystal panels are arranged such that light
from a back light arranged behind the liquid crystal panel 62 for a
slit barrier is transmitted through the liquid crystal panels. The
liquid crystal panel 62 for a slit barrier displays a slit image
having a high contrast ratio. The liquid crystal panel 61 for a
display displays multiple visual point images generated by computer
graphics in a state in which the multiple visual point images are
synthesized in a stripe shape. Thus, a stereoscopic image can be
observed according to the principle of the parallax barrier as
shown in FIG. 3. Namely, a parallax image 72 for a left-hand eye
and a parallax image 73 for a right-hand eye are displayed in a
stripe shape on a display panel 70. The left-hand eye can see only
the parallax image for a left-hand eye and the right-hand eye can
see only the parallax image for a right-hand eye when these
parallax images are observed through a slit barrier 71 arranged on
a front face of the display panel 70. Thus, a stereoscopic image
can be observed.
At this time, a Fresnel lens 63 is used to set an opening pitch to
be slightly smaller than an image pitch (see FIG. 2). This
structure is similar to the above structure of a lenticular system
in which the pitch of the cylindrical lens is slightly smaller than
that of a display pixel.
The lenticular lens is fixedly arranged in the three-dimensional
display unit of the lenticular system shown in FIG. 1. Therefore,
for example, it is necessary to remake the lenticular lens when the
two-eye type display is changed to a three-eye type display.
Similarly, it is necessary to remake the lenticular lens when
observation distances are changed. It is also necessary to remake
the lenticular lens when a display panel having a different pixel
pitch is used in the two-eye type display.
When a normal two-dimensional image is displayed in this general
example, images having reduced resolutions are separately observed
by left-hand and right-hand eyes. Accordingly, an observed image is
different from an originally displayed two-dimensional image.
When a used display panel and an observation position are
determined, the display unit is first simulated to design an
optimum lenticular lens for a simulating condition. However, it is
difficult to manufacture and attach the lenticular lens to the
display unit as simulated since there are problems about a
manufacturing technique of the lenticular lens at its manufacturing
time, or mechanical problems in attachment of the lenticular lens
to the display unit.
In contrast to this, the slit barrier is not fixed, but can be
easily moved in the three-dimensional display unit of a liquid
crystal parallax barrier system shown in FIG. 2. Accordingly, it is
possible to cope with an arbitrary three-dimensional image display
from the two-eye type to a multiple-eye type. The three-dimensional
display unit can be also used as a normal two-dimensional image
display unit in which no resolution is reduced. Further, it is
possible to display two-dimensional and three-dimensional images on
the same screen in a state in which these images ape mixed with
each other.
However, there ape some faults in the three-dimensional display
unit shown in FIG. 2. A first fault is a reduction in light amount
caused by the slit barrier so that the screen becomes dark. A
second fault is that the slit barrier becomes an eyesore obstacle
at the observing time of an image. To avoid this second fault, it
is necessary to set a pitch of slits of the slit barrier to be very
small. However, when the slit barrier is constructed by a liquid
crystal panel, the slit pitch is limited by a pixel pitch of the
liquid crystal panel when the slit pitch of the slit barrier is
reduced. Directivity of light is widened by a diffraction
phenomenon even when a sufficiently small slit pitch is obtained.
These two faults provide a limit of the parallax barrier system
irrespective of a structure in which the slit barrier is
constructed by a liquid crystal. Therefore, no parallax barrier
system is considered as a practical technique at present so that no
parallax barrier system is currently a main stream product
current.
A third fault of the three-dimensional display unit shown in FIG. 2
is that the three-dimensional display unit is large-sized in
comparison with a screen size. Further, a distance between the two
liquid crystal panels must be increased as an observation distance
is increased. Further, it is necessary to arrange a mechanical
device for moving the liquid crystal panels forward and backward in
accordance with a change in observation distance. A fourth fault of
the three-dimensional display unit shown in FIG. 2 is that
polarizing plates are required on both faces of each of the two
liquid crystal panels used in the three-dimensional display unit.
Accordingly, light from the back light is transmitted through a
total of four polarizing plates. Therefore, an amount of the
transmitted light is reduced since no transmittance of each of the
polarizing plates is equal to 100%. A strong back light is required
to compensate this reduced light amount. Accordingly, there are
various kinds of problems about the general technique of the
three-dimensional display unit.
FIG. 4 shows another general three-dimensional display unit using a
lenticular lens. In this three-dimensional display unit, the
lenticular lens is directly stuck onto the display face of a liquid
crystal panel 121. This three-dimensional display unit is of a
two-eye type in which two different parallax images are
simultaneously displayed in the liquid crystal panel. One portion
of a parallax image corresponding to a left-hand eye is displayed
in a display pixel D.sub.i1 of the liquid crystal panel 121. One
portion of a parallax image corresponding to a right-hand eye is
displayed in a display pixel D.sub.i2 of the liquid crystal panel
121. A cylindrical lens L.sub.i is arranged such that this
cylindrical lens corresponds to a pair of display pixels D.sub.i1
and D.sub.i2. Light is transmitted through the display pixels
D.sub.i1 and D.sub.i2 and is separated into light portions in
display spaces P and Q within an observation region by a converging
operation of the cylindrical lens L.sub.i. Light is similarly
separated into light portions with respect to index i from 1 to n.
Thus, the parallax image for the left-hand eye is converged in the
display space P and the parallax image for the right-hand eye is
converged in the display space Q. A stereoscopic image can be
observed when the left-hand and right-hand eyes are respectively
located in the display spaces P and Q.
As mentioned above, in the three-dimensional display unit of a
lenticular system, spaces capable of observing the stereoscopic
image are limited and are spaced from each other.
A three-dimensional display unit of a multiple-eye type for
regenerating many different parallax images is used in a certain
case to widen spaces capable of observing a stereoscopic image.
However, in this case, many different parallax images such as three
parallax images or more must be simultaneously displayed in a
liquid crystal panel 121. Accordingly, resolution of one parallax
image is greatly reduced since the number of display pixels in the
liquid crystal panel 121 is limited.
Therefore, another general three-dimensional display unit of a head
tracing type is developed to observe a stereoscopic image having
high resolution in a wider space. In this three-dimensional display
unit, the position of an observer's head is detected while a
stereoscopic image of the two-eye type is regenerated. A position
of the regenerated stereoscopic image is conformed to the
observer's head position.
For example, the observer's head position is photographed by a
video camera at any time. The position of a contour of an
observer's face or the position of an observer's eye is detected
from an image signal of the video camera. An operation of the
three-dimensional display unit is controlled such that the
regenerated stereoscopic image is displayed in this detected
position.
FIG. 5 is a view for explaining a basic principle of the
three-dimensional display unit of the head tracing type. A
lenticular lens 132 is arranged on the front face of a liquid
crystal panel 131. The regenerating principle of a stereoscopic
image is similar to that explained with reference to FIG. 4.
The differences between the regenerating principles shown in FIGS.
4 and 5 are that a lens moving device 133 is connected to the
lenticular lens 132 so as to change a relative position of the
lenticular lens 132 with respect to the liquid crystal panel 131.
When the relative position of the lenticular lens 132 with respect
to the liquid crystal panel 131 is changed, an emitting direction
of light emitted from each of cylindrical lenses constituting the
lenticular lens is changed by a converging action thereof so that
display positions P' and Q' in display spaces can be
controlled.
The lens moving device 133 is a device for exactly controlling a
position of the lenticular lens 132. Accordingly, the lens moving
device 133 is constructed by a precise mechanical system.
A regenerating position of the stereoscopic image is controlled by
moving the lenticular lens 132 such that this regenerating position
is in conformity with a detected observer's head position.
As mentioned above, in the general three-dimensional display unit
of the two-eye type, a space capable of observing the stereoscopic
image is greatly limited on the basis of the principle of the
lenticular system.
In the general three-dimensional display unit of the multiple-eye
type, the observation space of the stereoscopic image is widened in
accordance with multiple eyes. However, resolution of one parallax
image is reduced so that the quality of a regenerated stereoscopic
image is reduced.
Further, in the general three-dimensional display unit of the head
tracing type, relative positions of the liquid crystal panel and
the lenticular lens must be very exactly controlled. Therefore, a
precise mechanical system is used so that the three-dimensional
display unit is large-sized. Accordingly, a relatively large
lenticular lens is moved so that responsibility of position control
in a display space is reduced. Further, the lenticular lens is
moved only on a face parallel to the display panel so that a head
tracing range is also limited on this face.
The general three-dimensional display unit of the head tracing type
is of a two-eye type. Accordingly, no observed stereoscopic image
is moved even when the observer's head is moved. Therefore, no
natural stereoscopic image can be regenerated in this
three-dimensional display unit.
In the three-dimensional display unit of a direct viewing type as
another general example, a lenticular lens is directly stuck onto a
liquid crystal panel display face.
One cylindrical lens corresponding to a plurality of pixels of the
liquid crystal panel is prepared in the three-dimensional display
unit of the direct viewing type. One portion of different parallax
images is displayed in each of the plural pixels. Each of the
parallax images is separately formed in a certain space in an
observation region by a converging function of the cylindrical
lens. An observer can observe a stereoscopic image if the observer
sees the different parallax images by his right-hand and left-hand
eyes.
When a pitch of the plural pixels of the above liquid crystal panel
and a pitch of the cylindrical lens are equal to each other and all
cylindrical lenses have the same shape, the size of an observable
display screen is a small size about a distance between the
observer's eyes.
To increase the size of the display screen, it is necessary to
converge light emitted from a peripheral portion of the liquid
crystal panel to the observation space prescribed by the distance
between the observer's eyes. For example, a method for converging
this light to the observation space is shown in FIG. 6.
FIG. 6 shows an example of the three-dimensional display unit of a
two-eye type. In this three-dimensional display unit, one portion
of a parallax image for a left-hand eye is displayed in a pixel
G.sub.i1 of a liquid crystal panel 30. One portion of a parallax
image for a right-hand eye is displayed in a pixel G.sub.i2 of the
liquid crystal panel 30. Index i is set to a value from 1 to n. A
cylindrical lens L.sub.i is arranged in accordance with a pair of
pixels G.sub.i1 and G.sub.i2.
Light is transmitted through the pixels G.sub.i1 and G.sub.i2 and
is separated into light portions in display spaces I and J in the
observation region by a converging operation of the cylindrical
lens L.sub.i. A stereoscopic image can be observed when the
left-hand and right-hand eyes are respectively located in the
display spaces I and J.
In FIG. 8, the cylindrical lens L.sub.i has the same shape.
However, a pitch of the pair of pixels G.sub.i1 and G.sub.i2 is
different from a pitch of the cylindrical lens L.sub.i. The pitch
of the cylindrical lens L.sub.i is set to be slightly smaller than
the pitch of the pair of pixels G.sub.i1 and G.sub.i2.
A center of the pair of pixels G.sub.in is shifted from a center of
the corresponding cylindrical lens L.sub.i in a peripheral portion
of the liquid crystal panel 30. An amount of this shift is
increased as the shift is caused in the peripheral portion of the
liquid crystal panel 30. Incident angles of transmitted light of
the respective pixels G.sub.in incident to the cylindrical lens
L.sub.i are different from each other by this shift in central and
peripheral portions of the liquid crystal panel 30. Accordingly,
the transmitted light from the pixels G.sub.in in the peripheral
portion of the liquid crystal panel 30 can be converged into the
specified spaces I and J in the observation region.
However, the above general three-dimensional display unit as a flat
panel display has a wiring portion between pixels. No light is
transmitted through this wiring portion. Accordingly, it is
considered that black light is transmitted through this wiring
portion. In this case, this black light is converged between the
display spaces I and J in the specified observation region by a
converging principle similar to the above-mentioned converging
principle. This means that an unreachable region of the transmitted
light from the pixels exists between the display spaces I and
J.
FIG. 7 shows one example of the construction of a general flat
panel display of a three-eye type.
In the flat panel display shown in FIG. 7, a cylindrical lens
R.sub.i is arranged in proximity to display pixels Q.sub.i1,
Q.sub.i2 and Q.sub.i3 of a liquid crystal panel 40 such that the
cylindrical lens R.sub.i corresponds to these display pixels. The
transmitted light is converged and formed as a parallax image in
each of display spaces S, T and U within an observation region. No
light is transmitted through a wiring portion between pixels of the
liquid crystal panel so that this wiring portion forms a
non-transmitting portion P.sub.i.
This non-transmitting portion P.sub.i causes a space to which no
light is almost transmitted within the observation region. Namely,
non-display spaces V and W are formed in accordance with
non-transmitting portions P.sub.i1 and P.sub.i2.
An observer recognizes each of the non-display spaces V and W as a
black band. The observer sees the black band as a non-display
portion at any time when the observer moves his head and an
observed stereoscopic image is changed from a combination of the
display spaces S and T to a combination of the display spaces T and
U.
FIG. 8 shows a light intensity distribution of a projecting pattern
which is obtained by converging the transmitted light of each of
the display pixels by the cylindrical lens R.sub.i and is taken
along a cutting plane b-b' in FIG. 7.
In FIG. 8, the width of a non-display portion is widened in
comparison with an ideal state. Accordingly, there is a problem
that this widened non-display portion becomes a great obstacle when
a continuous stereoscopic image is observed.
FIG. 9a is a plan view showing a liquid crystal panel 91. FIG. 9b
is a cross-sectional view showing a lenticular lens 92
corresponding to the liquid crystal panel 91 shown in FIG. 9a.
FIGS. 9a and 9b show a two-eye type. With respect to the liquid
crystal panel 91, a scanning operation is performed in a vertical
direction such that a main scanning line is in conformity with the
longitudinal direction of a cylindrical lens within the lenticular
lens 92. The liquid crystal panel 91 displays images for right-hand
and left-hand eyes in a mixing state every other main scanning
line. Namely, the image for the right-hand eye is displayed on each
of odd horizontal scanning lines such as (1), (3), (5), (7), - - -
. The image fop the left-hand eye is displayed on each of even
horizontal scanning lines such as (2), (4), (6), (8), - - - .
A projected image of the image for the left-hand eye shown in FIG.
10a is displayed by a converging action of the lenticular lens 92
stuck to a front face of the liquid crystal panel 91 in a certain
space in an observation region. A projected image of the image for
the right-hand eye shown in FIG. 10b is displayed in a spatial
portion adjacent to this certain space.
When a direct current voltage is continuously applied to the liquid
crystal panel, electrolysis of liquid crystal molecules is caused
so that the liquid crystal panel is finally unoperated. Therefore,
an alternating current voltage is normally applied to the liquid
crystal panel. A system for applying the alternating current
voltage to the liquid crystal panel is constructed by two systems
composed of a line inverting system shown in FIG. 11a and a frame
inverting system shown in FIG. 11b.
In the line inverting system shown in FIG. 11a, a voltage having
positive and negative polarities is applied to the liquid crystal
panel every one line (one horizontal period). In contrast to this,
in the frame inverting system shown in FIG. 11b, a voltage having
positive and negative polarities is applied to the liquid crystal
panel every one frame (one vertical period).
As mentioned above, in the general voltage applying technique, the
positive and negative polarities are inverted in the frame
inverting system or the line inverting system. In the frame
inverting system, the images for the left-hand and right-hand eyes
respectively shown in FIGS. 10a and 10b and projected in the
stereoscopic observation space are displayed by a positive or
negative voltage having the same polarity. The images for the
left-hand and right-hand eyes are displayed in the next frame by a
negative or positive voltage having a polarity inverse to the
previous polarity.
The images for the left-hand and right-hand eyes are
instantaneously displayed by the same polarity at any time.
However, in view of a change in time, the voltage polarities are
repeatedly inverted every frame with respect to the images for the
left-hand and right-hand eyes. A slight difference in voltage
setting is caused by a difference between the voltage polarities so
that a flicker phenomenon is caused. In this flicker phenomenon,
light and dark portions are periodically repeated.
In the line inverting system, the image for the left-hand eye shown
in FIG. 10a and projected in the stereoscopic observation space in
a frame at a certain time is displayed by the same voltage polarity
with respect to all lines. The image for the right-hand eye shown
in FIG. 10b is also displayed by the same voltage polarity with
respect to all lines. However, the voltage polarities with respect
to the images for the left-hand and right-hand eyes are different
from each other. The voltage polarities are inverted in the next
frame with respect to each of the images for the left-hand and
right-hand eyes. Therefore, the polarities of the applied voltage
are also different from each other in the next frame with respect
to the images for the left-hand and right-hand eyes.
Accordingly, the polarities of the applied voltage are different
from each other in a frame at the same time with respect to the
images for the left-hand and right-hand eyes so that a difference
in brightness between the images for the left-hand and right-hand
eyes is caused. Therefore, when an observer sees a stereoscopic
image, images having different brightnesses are observed by the
left-hand and right-hand eyes so that fatigue of the observer is
increased.
SUMMARY OF THE INVENTION
It is therefore a first object of the present invention to provide
a three-dimensional display unit without any spectacles in which it
is possible to cope with an arbitrary three-dimensional image
display from a two-eye type to a multiple-eye type, and an
observation region can be freely moved forward, backward, rightward
and leftward, and the three-dimensional display unit can be also
used as a normal two-dimensional image display unit reducing no
resolution, and two-dimensional and three-dimensional images can be
displayed on the same screen in a mixing state, and parallax images
can be displayed in a vertical direction in addition to a
horizontal direction.
A second object of the present invention is to provide a
three-dimensional display unit in which the three-dimensional
display unit is of a head tracing type without including any
mechanical system and a region for observing a stereoscopic image
is greatly widened and the stereoscopic image is regenerated with
high resolution and high quality.
A third object of the present invention is to provide a
three-dimensional display unit in which a stereoscopic image
conforming to the position of an observer's head is regenerated and
can be naturally observed in addition to the second object.
A fourth object of the present invention is to provide a
three-dimensional display unit in which light reaches a non-display
space between display spaces within an observation region, and no
black band is seen between parallax images.
A fifth object of the present invention to provide a
three-dimensional display unit in which it is possible to generate
images for left-hand and right-hand eyes having no change with the
passage of time and no change in brightness therebetween, and a
stereoscopic image can be observed with high quality and reduced
fatigue.
In accordance with a first construction of the present invention,
the above first object can be achieved by a three-dimensional
display unit comprising display means for simultaneously displaying
a plurality of different parallax images; and optical means
attached to the display means and formed by an array of cylindrical
lenses such that a transparent substance having high flexibility is
supported by transparent electrodes from both substance sides, and
optical characteristics of each of the cylindrical lenses can be
changed by applying a voltage to the transparent substance to
change at least one surface shape of the transparent substance.
The optical characteristics include a focal length.
In accordance with a seventh construction of the present invention,
the above first object can be also achieved by a three-dimensional
display unit comprising display means for simultaneously displaying
a plurality of different parallax images; and optical means
attached to the display means and formed by an array of cylindrical
lenses such that a transparent substance having a refractive index
changed by a voltage applied to this transparent substance is
supported by transparent electrodes from both substance sides, and
optical characteristics of each of the cylindrical lenses can be
changed by applying the voltage to the transparent substance to
provide a refractive index distribution for the transparent
substance.
In accordance with an eighth construction of the present invention,
the optical means is constructed by a liquid crystal.
In accordance with a ninth construction of the present invention,
the optical means acts as a two-dimensional lens array.
In the first construction of the three-dimensional display unit,
the display means simultaneously displays a plurality of different
parallax images. The optical means is attached onto a front face of
the display means. The optical means is constructed such that a
transparent substance having high flexibility is supported by
transparent electrodes from both substance sides. In the optical
means realizing a cylindrical lens array, optical characteristics
of each of the cylindrical lenses can be changed by applying a
voltage to the transparent substance to change at least one surface
shape of the transparent substance. The plural parallax images
displayed by the display means are spatially separated from each
other and are projected to a certain observation space by a
converging action of this cylindrical lens array. An observer
simultaneously sees the different parallax images by different eyes
so that a stereoscopic image is observed. The optical
characteristics of the optical means can be changed by changing a
pattern of the applied voltage. Accordingly, lens parameters such
as a lens curvature radius, a lens thickness and a lens pitch are
arbitrarily set in a state in which the optical means is mounted to
the display means. Further, a region having no lens action is
realized by arranging a region in which no voltage is partially
applied to the transparent substance.
In the seventh construction of the three-dimensional display unit,
the display means simultaneously displays a plurality of different
parallax images. The optical means is attached onto a front face of
the display means. The optical means is constructed such that a
transparent substance having a refractive index changed by a
voltage applied to this transparent substance is supported by
transparent electrodes from both substance sides. In the optical
means realizing a cylindrical lens array, optical characteristics
of each of the cylindrical lenses can be changed by applying the
voltage to the transparent substance to provide a refractive index
distribution for the transparent substance. The plural parallax
images displayed by the display means are spatially separated from
each other and are projected to a certain observation space by a
converging action of this cylindrical lens array. An observer
simultaneously sees the different parallax images by different eyes
so that a stereoscopic image is observed. The optical
characteristics of the optical means can be changed by changing a
pattern of the applied voltage. Accordingly, lens parameters such
as a lens curvature radius, a lens thickness and a lens pitch are
arbitrarily set in a state in which the optical means is mounted to
the display means. Further, a region having no lens action is
realized by arranging a region in which no voltage is partially
applied to the transparent substance.
In the eighth construction of the three-dimensional display unit,
the optical means is constructed by a liquid crystal so that the
optical characteristics of the optical means can be greatly changed
at a smaller voltage by electrooptic effects.
In the ninth construction of the three-dimensional display unit,
the optical means acts as a two-dimensional lens array so that it
is possible to observe a stereoscopic image having a parallax in a
vertical direction in addition to a horizontal direction.
In accordance with a fourteenth construction of the present
invention, the above second object can be achieved by a
three-dimensional display unit comprising display means for
simultaneously displaying a plurality of different parallax images;
optical means attached to the display means and constructed by an
array of cylindrical lenses such that optical characteristics of
each of the cylindrical lenses can be changed; detecting means for
detecting a spatial position of an observer's head; and control
means connected to the detecting means and controlling an operation
of the optical means based on position information of the
observer's head detected by the detecting means such that a
stereoscopic image is regenerated in an optimum position of the
observer's head.
In accordance with a nineteenth construction of the present
invention, the above third object can be achieved by a
three-dimensional display unit comprising display means for
simultaneously displaying a plurality of different parallax images;
optical means attached to the display means and constructed by an
array of cylindrical lenses such that optical characteristics of
each of the cylindrical lenses can be changed; detecting means for
detecting a spatial position of an observer's head; control means
connected to the detecting means and controlling an operation of
the optical means based on position information of the observer's
head detected by the detecting means such that a stereoscopic image
is regenerated in an optimum position of the observer's head; a
plurality of stereoscopic signal sources for performing a
multiple-eye display; and selecting means connected to the plural
stereoscopic signal sources and the detecting means and selecting a
stereoscopic signal displayed to the display means on the basis of
the position information of the observer's head detected by the
detecting means.
In accordance with a twentieth construction of the present
invention, the optical means is constructed by a liquid
crystal.
In accordance with a twenty-first construction of the present
invention, a projecting lens and a diffusive layer are arranged
between the display means and the optical means.
In the three-dimensional display unit having the fourteenth
construction, a plurality of different parallax images are
simultaneously displayed in the display means in every other array
of display pixels arranged in one line. The optical means is
attached to an upper face of the display means. The optical means
is constructed by an array of cylindrical lenses having optical
characteristics electrically controlled. The plural parallax images
displayed in the display means are separated from each other by a
converging action of the optical means and are projected into a
certain observation region. An observer can observe a stereoscopic
image if the different parallax images are simultaneously seen by
different eyes. The detecting means detects a spatial position of
the observer's head. The control means receives position
information of the observer's head from the detecting means and
controls the optical characteristics of the optical means based on
this position information such that the stereoscopic image is
regenerated in an optimum position.
In the three-dimensional display unit having the nineteenth
construction, a plurality of different parallax images are
simultaneously displayed in the display means in every other array
of display pixels arranged in one line. The plurality of
stereoscopic signal sources are prepared to perform a multiple-eye
display. A stereoscopic signal displayed in the display means is
selected by the selecting means. The optical means is attached onto
an upper face of the display means. The optical means is
constructed by an array of cylindrical lenses having optical
characteristics electrically controlled. The plural parallax images
displayed in the display means are separated from each other by a
converging action of the optical means and are projected into a
certain observation region. An observer can observe a stereoscopic
image if the different parallax images are simultaneously seen by
different eyes. The detecting means detects a spatial position of
the observer's head. The control means receives position
information of the observer's head from the detecting means and
controls the optical characteristics of the optical means based on
this position information such that the stereoscopic image is
regenerated in an optimum position. Further, the selecting means
receives the position information of the observer's head from the
detecting means and selects a stereoscopic signal conforming to
this head position and displays this stereoscopic signal in the
display means.
In the three-dimensional display unit having the twentieth
construction, the optical means is constructed by a liquid crystal.
Accordingly, the refractive index of a cylindrical lens can be
greatly changed so that optical characteristics of the cylindrical
lens can be changed at a low voltage.
In the three-dimensional display unit having the twenty-first
construction, a projecting lens and a diffusive layer are arranged
between the display means and the optical means. Accordingly, it is
possible to provide a three-dimensional display unit of a
projecting type for enabling a large-sized screen display.
In accordance with a third construction of the present invention,
the above fourth object can be achieved by a three-dimensional
display unit comprising display means having a plurality of pixels
and a non-transmitting portion and simultaneously displaying a
plurality of parallax images and emitting light from each of the
pixels; masking means attached to a surface of the display means
and arranged at the same pitch as a pitch of the respective pixels
in accordance with the non-transmitting portion of the display
means; the masking means having an unopen portion constructed such
that one portion of light emitted from each of the pixels is
incident to the unopen portion and is emitted from the unopen
portion by changing an optical path of the incident light by the
unopen portion; and lens means constructed by an array of
cylindrical lenses each having the same shape and attached to a
surface of the masking means.
In accordance with a fourth construction of the present invention,
the unopen portion of the masking means has a light interrupting
film for reducing the size of a non-display space corresponding to
the non-transmitting portion of the display means.
In the third construction of the three-dimensional display unit,
the display means has a plurality of pixels and a non-transmitting
portion and simultaneously displays a plurality of parallax images
and emits light from each of the pixels. The masking means is
attached to a surface of the display means and is arranged at the
same pitch as a pitch of the respective pixels in accordance with
the non-transmitting portion of the display means. An unopen
portion of the masking means is constructed such that one portion
of light emitted from each of the pixels is incident to the unopen
portion and is emitted from the unopen portion by changing an
optical path of the incident light by the unopen portion. The lens
means is constructed by an array of cylindrical lenses each having
the same shape and attached to a surface of the masking means. The
lens means allocates emitted lights from adjacent display pixels to
different display spaces.
In the fourth construction of the three-dimensional display unit, a
light interrupting film arranged in the unopen portion of the
masking means reduces the size of a non-display space corresponding
to the non-transmitting portion of the display means.
In accordance with a fifth construction of the present invention,
the above fifth object can be achieved by a three-dimensional
display unit comprising display means for simultaneously displaying
a predetermined number of different parallax images; and optical
means constructed by an array of cylindrical lenses such that a
longitudinal direction of each of the cylindrical lenses is equal
to a vertical direction; the three-dimensional display unit being
constructed such that the display means scans a main scanning line
thereof in the vertical direction such that this main scanning line
is in conformity with the longitudinal direction of each of the
cylindrical lenses; the polarities of a voltage applied to the
display means are inverted on the main scanning line every
predetermined number of parallax images; and the voltage having a
polarity inverse to that in the previous frame is repeatedly
applied to the display means in the next frame every main scanning
line.
In accordance with a sixth construction of the present invention,
the display means inverts the voltage polarities every one main
scanning line when the number of different parallax images is equal
to an odd number, and the voltage having a polarity inverse to that
in the previous frame is repeatedly applied to the display means in
the next frame every main scanning line.
In the fifth construction of the three-dimensional display unit,
the display means and the optical means are arranged such that a
main scanning line of the display means is in conformity with the
longitudinal direction of a cylindrical lens within the optical
means. The display means simultaneously displays a predetermined
number of different parallax images every other main scanning line.
One cylindrical lens within the optical means corresponds to one
set of the predetermined number of main scanning lines. The
polarities of a voltage applied to the display means are inverted
on the main scanning line every predetermined number of parallax
images. Light emitted from the display means is separated into
light portions by a converging operation of the optical means every
parallax image. Thus, different parallax images are projected into
different spaces. Each of the projected images is formed as an
image having a polarity inverting pattern every one main scanning
line. Further, an image provided by a voltage polarity inverse to
that provided in the previous pattern is formed in the next
frame.
When the number of parallax images is equal to an odd number, the
voltage polarities are inverted every one main scanning line of the
display means. An image separated and projected by the optical
means has a polarity inverting pattern every one main scanning
line. Further, an image provided by a voltage polarity inverse to
that provided in the previous pattern is formed in the next
frame.
Further objects and advantages of the present invention will be
apparent from the following description of the preferred
embodiments of the present invention as illustrated in the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view showing the structure of a general
three-dimensional display unit of a lenticular system as one
constructional example;
FIG. 2 is a schematic view showing one constructional example of a
general three-dimensional display unit of a liquid crystal parallax
barrier system;
FIG. 3 is a view for illustrating the principle of the parallax
barrier system;
FIG. 4 is a cross-sectional view showing the structure of another
general three-dimensional display unit;
FIG. 5 is a cross-sectional view showing the structure of a general
three-dimensional display unit of a head tracing type;
FIG. 6 is a cross-sectional view showing one constructional example
of a general three-dimensional display unit of a two-eye type;
FIG. 7 is a cross-sectional view showing one constructional example
of a general three-dimensional display unit of a three-eye
type;
FIG. 8 is a view for explaining light intensity of the general
three-dimensional display unit of the three-eye type shown in FIG.
7;
FIGS. 9a and 9b are schematic views showing another constructional
example of the general three-dimensional display unit of a two-eye
type;
FIGS. 10a and 10b are views for explaining images for left-hand and
right-hand eyes respectively projected to the left-hand and
right-hand eyes of an observer from a liquid crystal panel shown in
FIGS. 9a and 9b;
FIGS. 11a and 11b are views for explaining a general line inverting
system and a general frame inverting system;
FIG. 12 is a cross-sectional view showing the basic structure of a
three-dimensional display unit in accordance with one embodiment of
the present invention;
FIG. 13 is an enlarged cross-sectional view showing one
constructional example of an optical characteristic variable lens
used in the three-dimensional display unit shown in FIG. 12;
FIGS. 14a to 14c are views for explaining a mixing display of
two-dimensional and three-dimensional images;
FIG. 15 is an enlarged cross-sectional view showing another
constructional example of an optical characteristic variable lens
used in the three-dimensional display unit shown in FIG. 12;
FIG. 18 is an explanatory graph showing a refractive index
distribution of the optical characteristic variable lens shown in
FIG. 15;
FIG. 17 is an explanatory view showing one electrode arrangement
used for the optical characteristic variable lens shown in FIG.
15;
FIG. 18 is an explanatory view showing another electrode
arrangement used for the optical characteristic variable lens shown
in FIG. 15;
FIG. 19 is an explanatory view showing one correspondence between a
change in parallax image number and control of the optical
characteristic variable lens;
FIG. 20 is an explanatory view showing another correspondence
between a change in parallax image number and control of the
optical characteristic variable lens;
FIG. 21 is a cross-sectional view showing the basic construction of
a three-dimensional display unit in accordance with another
embodiment of the present invention;
FIG. 22 is a view for explaining each of variables showing optical
characteristics of a cylindrical lens used in the three-dimensional
display unit shown in FIG. 21;
FIG. 23 is an explanatory view showing the relation between a
display pixel and a projected image in the three-dimensional
display unit shown in FIG. 21;
FIG. 24 is an explanatory view showing the relation between a pitch
of the display pixel and the pitch of a lenticular lens in the
three-dimensional display unit shown in FIG. 21;
FIG. 25 is an explanatory view showing the relation between a
position of the projected image and a shifting amount of a relative
position of the display pixel and the lenticular lens in the
three-dimensional display unit shown in FIG.
FIG. 26 is a cross-sectional view showing the basic structure of a
three-dimensional display unit in accordance with another
embodiment of the present invention;
FIG. 27 is a view for schematically explaining one example of a
photographing system used in the three-dimensional display unit
shown in FIG. 26;
FIG. 28 is a cross-sectional view showing the basic structure of a
three-dimensional display unit of a projecting type;
FIG. 29a is a cross-sectional view showing the construction of a
three-dimensional display unit in accordance with another
embodiment of the present invention;
FIG. 29b is a view enlargedly showing one portion of the
three-dimensional display unit shown in FIG. 29a;
FIG. 30 is a view for explaining light intensity of the
three-dimensional display unit shown in FIGS. 29a and 29b;
FIG. 31 is an enlarged cross-sectional view showing the
construction of a three-dimensional display unit in accordance with
another embodiment of the present invention;
FIG. 32 is an enlarged cross-sectional view showing the
construction of a three-dimensional display unit in accordance with
another embodiment of the present invention;
FIG. 33 is an enlarged cross-sectional view showing the
construction of a three-dimensional display unit in accordance with
another embodiment of the present invention;
FIG. 34 is an enlarged cross-sectional view showing the
construction of a three-dimensional display unit in accordance with
another embodiment of the present invention;
FIG. 35a is an enlarged cross-sectional view showing the
construction of a three-dimensional display unit in accordance with
another embodiment of the present invention;
FIG. 35b is a view enlargedly showing one portion of the
three-dimensional display unit shown in FIG. 35a;
FIG. 36 is an enlarged cross-sectional view of the
three-dimensional display unit shown in FIGS. 35a and 35b;
FIG. 37 is a view for explaining light intensity of the
three-dimensional display unit shown in FIGS. 35a and 35b;
FIGS. 38a and 38b are views showing the schematic construction of a
three-dimensional display unit of a two-eye type in accordance with
another embodiment of the present invention;
FIG. 39 is a cross-sectional view showing a structure of the
three-dimensional display unit shown in FIGS. 38a and 38b;
FIG. 40 is an explanatory view showing a polarity inverting pattern
of a liquid crystal panel shown in FIGS. 38a and 38b;
FIGS. 41a and 41b are views for explaining images for left-hand and
right-hand eyes respectively projected to the left-hand and
right-hand eyes of an observer from the liquid crystal panel shown
in FIGS. 38a and 38b;
FIGS. 42a and 42b are views showing the schematic construction of a
three-dimensional display unit of a three-eye type in accordance
with another embodiment of the present invention;
FIG. 43 is a view fop explaining a polarity inverting pattern of a
liquid crystal panel shown in FIGS. 42a and 42b;
FIGS. 44a, 44b and 44c are views for respectively explaining
parallax images A, B and C projected from the liquid crystal panel
shown in FIGS. 42a and 42b; and
FIG. 45 is a schematic constructional view showing the basic
structure of a three-dimensional display unit in accordance with
another embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The preferred embodiments of a three-dimensional display unit in
the present invention will next be described in detail with
reference to the accompanying drawings.
FIG. 12 is a cross-sectional view showing the basic structure of a
three-dimensional display unit in accordance with a first
embodiment of the present invention.
The three-dimensional display unit shown in FIG. 12 is of a two-eye
type and is of a direct viewing type in which an optical
characteristic variable lens is arranged on the front face of a
flat display panel. The three-dimensional display unit is
constructed such that a regenerating space of a stereoscopic image
can be electrically controlled.
The three-dimensional display unit shown in FIG. 12 is constructed
by a liquid crystal panel 1 as a display means, an optical
characteristic variable lens 2 as an optical means, an optical
characteristic variable lens control section 3 and a remote
controller 4. The optical characteristic variable lens 2 is
arranged such that the optical characteristic variable lens 2 is
closely attached to the liquid crystal panel 1. The optical
characteristic variable lens control section 3 is connected to the
optical characteristic variable lens 2. The remote controller 4 is
connected to the optical characteristic variable lens control
section 3. In the real three-dimensional display unit, an
illuminating light source for a display is arranged on a rear face
of the liquid crystal panel 1, but is omitted in FIG. 12.
A color liquid crystal panel is normally used as the liquid crystal
panel 1. In this case, an array of color filters in the liquid
crystal panel is set such that red, green and blue (RGB) are
arranged in a vertical direction (up-and-down direction) on the
screen so as not to separate color images from each other by a lens
action.
In the liquid crystal panel 1, two different parallax images are
displayed in a stripe shape every other pixel. One portion of a
parallax image (for a left-hand eye) corresponding to a left-hand
eye is displayed in a pixel D.sub.i1 of the liquid crystal panel 1
and one portion of a parallax image (for a right-hand eye)
corresponding to a right-hand eye is displayed in a pixel D.sub.i2
of the liquid crystal panel 1. Index i is set to a value from 1 to
n.
In the first embodiment shown in FIG. 12, the liquid crystal panel
is used as an image display panel. However, the three-dimensional
display unit can be constructed by using an electroluminescence
(EL) panel, a plasma display, a flat panel display of a light
emitting diode (LED) array, etc. In this case, it is not necessary
to arrange an illuminating light source for a display.
The optical characteristic variable lens 2 is a lens having the
same converging action as a lenticular lens. Optical
characteristics of the optical characteristic variable lens 2 can
be electrically controlled. The optical characteristic variable
lens 2 is constructed by an array of cylindrical lenses L.sub.i. A
cross section of a cylindrical lens L.sub.i is shown in FIG. 12 and
a longitudinal direction of the cylindrical lens L.sub.i is in
conformity with a direction perpendicular to a paper face. The
longitudinal direction of the cylindrical lens L.sub.i is set such
that this longitudinal direction is in conformity with an array
direction of pixels displaying the same parallax images in the
liquid crystal panel 1. The optical characteristic variable lens 2
will be described later in detail.
The cylindrical lens L.sub.i within the optical characteristic
variable lens 2 corresponds to a pair of pixels D.sub.i1 and
D.sub.i2 within the liquid crystal panel 1. The cylindrical lens
L.sub.i is arranged such that the cylindrical lens L.sub.i is
closely attached to the pixels D.sub.i1 and D.sub.i2. Light is
transmitted through the pixels D.sub.i1 and D.sub.i2 and is
separated into light portions by a converging operation of the
cylindrical lens L.sub.i. These light portions are projected into
display spaces P and Q in an observation region. Light is similarly
separated and projected with respect to all the pixels from 1 to n.
Thus, the display space P for projecting the parallax image for the
left-hand eye and the display space Q for projecting the parallax
image for the right-hand eye are formed. An observer can observe a
stereoscopic image when the left-hand and right-hand eyes are
respectively located in the display spaces P and Q. Positions of
the display spaces P and Q can be controlled by changing the
relation in relative position between the pixels D.sub. i1,
D.sub.i2 and the cylindrical lens L.sub.i.
FIG. 13 shows one constructional example of the above optical
characteristic variable lens.
In FIG. 13, a transparent entire face electrode 23 is formed on a
glass substrate 24. The entire face electrode 23 is constructed by
a transparent film made of indium tin oxide (ITO), etc.
A transparent object 20 having high flexibility is laminated and
formed on the entire face electrode 23. When the transparent object
20 is fluidized, a transparent film 21 is formed on the transparent
object 20 such that no transparent object 20 flows out of the
entire face electrode 23. The transparent film 21 is thin and
flexible. For example, the transparent object 20 is constructed by
using silicon rubber or oil.
Many strip-shaped electrodes 22 are arranged between the
transparent object 20 and the transparent film 21. FIG. 13 shows a
cross section of each of the strip-shaped electrodes Each of the
strip-shaped electrodes 22 longitudinally extends in a direction
perpendicular to a paper face. Each of the strip-shaped electrodes
22 is also formed by a transparent film made of ITO, etc. Each of
the strip-shaped electrodes 22 is connected to an unillustrated
driving circuit. The entire face electrode 23 is also connected to
the driving circuit.
A surface of the transparent object 20 is initially set to be
planar. A voltage is partially applied to the strip-shaped
electrodes 22 so that the surface of the transparent object 20 or a
surface of the transparent film 21 is formed in convex and concave
shapes by electrostatic force applied between the entire face
electrode 25 and the strip-shaped electrodes 22. Namely, a voltage
having a polarity inverse to the polarity of a voltage applied to
the entire face electrode 23 is applied to strip-shaped electrodes
22b spaced from each other at a constant distance. Then, a voltage
having the same polarity as the voltage applied to the entire face
electrode 23 is applied to a strip-shaped electrode 22a located in
an intermediate position of this constant distance. Electrostatic
attractive force is applied between one strip-shaped electrode 22b
and the entire face electrode 23 so that a distance between the
strip-shaped electrode 22b and the entire face electrode 23 is
reduced. Conversely, electrostatic repulsive force is applied
between the strip-shaped electrode 22a and the entire face
electrode 23 so that a distance between the strip-shaped electrode
22a and the entire face electrode 23 is increased. The flexible
transparent object 20 is deformed by changes in these distances.
Thus, a cylindrical face is periodically formed in the optical
characteristic variable lens so that a lenticular lens is
constructed.
Convex and concave portions (or irregularities) of the cylindrical
face required for the lenticular lens are set to about 1 mm in
length. When the transparent object 20 is deformed at a low
voltage, it is effective to increase the strength of an electric
field caused between one strip-shaped electrode 22 and the entire
face electrode 25. The distance between the strip-shaped electrode
22 and the entire face electrode 23 is preferably set to about 1.5
mm in an initial planar state. It is necessary to set an entire
thickness of the optical characteristic variable lens to a certain
thickness to form the lenticular lens, but this thickness is
adjusted by a thickness of the glass substrate 24.
No strip-shaped electrode 22 applying a voltage thereto is limited
to the strip-shaped electrodes 22a and 22b. A voltage may be
applied in a certain voltage pattern to a series of strip-shaped
electrodes 22.
A shape, curvature and a thickness of the cylindrical face are
controlled by a pattern shape of the voltage applied to the
strip-shaped electrode 22. A period of the cylindrical face is
controlled by a pattern period of the voltage applied to the
strip-shaped electrode 22. A forming position of the cylindrical
face is controlled by shifting the pattern of the voltage applied
to the strip-shaped electrode 22. Thus, the shape and position of
the cylindrical face formed on the surface of the transparent
object 20 or the transparent film 21 can be controlled by the
pattern of the voltage applied to the strip-shaped electrode
An operation of the optical characteristic variable lens will next
be explained with reference to FIGS. 19 and 20 when the number of
displayed parallax images is changed. FIG. 19 shows the case of a
two-eye type. In the case of the two-eye type, two different
parallax images are alternately displayed on a display panel in a
stripe shape. Accordingly, a surface shape of the optical
characteristic variable lens is formed such that two pixels of the
display panel correspond to one cylindrical face of the optical
characteristic variable lens. FIG. 19 also shows the pattern of a
voltage applied to the strip-shaped electrode at this time in a
case in which the entire face electrode has a negative
potential.
The two-eye type is changed to a three-eye type as shown in FIG.
20. In the case of the three-eye type, three different parallax
images are repeatedly displayed on the display panel in a stripe
shape. Accordingly, a surface shape of the optical characteristic
variable lens is formed such that three pixels of the display panel
correspond to one cylindrical face of the optical characteristic
variable lens. FIG. 20 also shows the pattern of a voltage applied
to the strip-shaped electrode at this time in a case in which the
entire face electrode has a negative potential. Thus, it is
possible to cope with a three-dimensional image display
corresponding to an arbitrary number of parallax images by changing
pitches of concave and convex portions of the surface shape of the
optical characteristic variable lens. In FIGS. 19 and 20, in
reality, each of the pitches of concave and convex portions of the
surface shape of the optical characteristic variable lens is set to
be slightly smaller than a pixel pitch of the display panel.
In the general three-dimensional display unit of a lenticular
system, an observation position is determined by optical
characteristics of the lenticular lens mounted to the
three-dimensional display unit so that no observer can positively
move the observation position. However, in the three-dimensional
display unit in this embodiment, the optical characteristics of the
optical characteristic variable lens can be changed by remote
control using the remote controller so that the observer can freely
set the observation position at his own will. For example, the
optical characteristics of the optical characteristic variable lens
include a focal length.
When the observation region is moved forward, backward, rightward
or leftward in FIG. 12, moving direction and distance of the
optical characteristic variable lens are transmitted to the optical
characteristic variable lens control section 3 by the remote
controller 4. Thus, the optical characteristic variable lens
control section 3 calculates the pattern of a voltage applied to
the strip-shaped electrode 22 shown in FIG. 13 and changes a shape
of the optical characteristic variable lens through the driving
circuit. In this embodiment, all control operations of the optical
characteristics of the optical characteristic variable lens can be
electrically performed so that no mechanical portion is required.
The remote controller 4 can be set to a wired controller or a
wireless controller using infrared rays, etc.
No convex and concave portions (or irregularities) are formed on a
surface of the above optical characteristic variable lens in a
region in which no voltage is applied to the optical characteristic
variable lens. Accordingly, no lens action is caused in this
region. Therefore, a normal two-dimensional image can be displayed
in this region in which no voltage is applied to the optical
characteristic variable lens. Accordingly, as shown in FIG. 14a, it
is possible to display two-dimensional and three-dimensional images
in a state in which these images are mixed with each other.
A strip-shaped electrode perpendicular to the strip-shaped
electrode 22 can be used instead of the entire face electrode 23 in
FIG. 13. In this case, images can be controlled in a vertical
direction (up-and-down direction) on the screen. Accordingly, as
shown in FIG. 14b, a three-dimensional image can be displayed as a
window within a two-dimensional image. Further, as shown in FIG.
14c, a two-dimensional image can be displayed as a window within a
three-dimensional image. In this case, it is necessary to scan the
strip-shaped electrode at a high speed.
In the above description, the optical characteristic variable lens
is used as a lenticular lens having no parallax in the vertical
direction. However, when the above-mentioned perpendicular
electrode arrangement is used, the optical characteristic variable
lens can be used as a fly eye lens (a two-dimensional lens array)
having a parallax in the vertical direction.
FIG. 15 is a cross-sectional view showing the structure of an
optical characteristic variable lens in accordance with another
embodiment of the present invention. FIG. 15 shows one portion of
the optical characteristic variable lens using a liquid
crystal.
In FIG. 15, an array 11 of strip-shaped electrodes 11a, 11b, 11c, -
- - is formed on a glass substrate 13. An indium tin oxide (ITO)
film, etc. in the electrode array 11 are constructed by a
transparent film. FIG. 15 shows a cross section of each of the
strip-shaped electrodes 11a, 11b, 11c, - - - and each of these
strip-shaped electrodes longitudinally extends in a direction
perpendicular to a paper face. A transparent entire face electrode
12 is formed on another glass substrate 14. The entire face
electrode 12 is also formed by a transparent film made of ITO,
etc.
When a liquid crystal panel is used as a display element and a
pixel pitch is reduced by narrowing an electrode width, the number
of scanning electrodes is increased and an electrode resistance is
increased in a case of the same screen size. Accordingly, a
response speed of the liquid crystal panel is reduced so that no
pixel pitch can be extremely reduced. However, when the optical
characteristic variable lens is constructed as shown in FIG. 15,
the entire face electrode is formed on one side of the optical
characteristic variable lens so that it is not necessary to perform
a scanning operation. The optical characteristic variable lens is
used in a steady state so that no high response speed is required
for the liquid crystal panel in comparison with a case in which the
liquid crystal panel is used for a display. Therefore, it is
possible to realize a narrow electrode width and a small pixel
pitch in comparison with the liquid crystal panel for a
display.
The strip-shaped electrodes 11a, 11b, 11c, - - - and the entire
face electrode 12 are respectively connected to a liquid crystal
driving circuit as shown in FIG. 17. In FIG. 17, a strip-shaped
electrode 31 is connected to a strip-shaped electrode driving
circuit 33 and an entire face electrode 32 is connected to an
entire face electrode driving circuit 34. Operations of the
strip-shaped electrode driving circuit 33 and the entire face
electrode driving circuit 34 are controlled such that a desirable
voltage is applied to each of the strip-shaped electrode 31 and the
entire face electrode 32 by a control circuit 35.
A liquid crystal 10 is sealed between the electrode array 11 and
the entire face electrode 12. A liquid crystal molecule 10' of the
liquid crystal 10 is orientated in a uniform state in which the
liquid crystal molecule is parallel or perpendicular to the glass
substrates in an initial state.
A refractive index of the liquid crystal molecule 10' in the
direction of a molecular axis is different from that in a direction
perpendicular to the molecular axis. Therefore, the liquid crystal
molecule 10' shows optical anisotropy. An inclination angle of the
liquid crystal molecule 10' with respect to each of the glass
substrates 13 and 14 is changed by a voltage applied between the
electrode array 11 and the entire face electrode 12 so that the
refractive index of an aggregation of liquid crystal molecules 10'
is changed. Namely, a refractive index distribution of the optical
characteristic variable lens can be controlled by controlling the
voltage applied to the liquid crystal.
FIG. 19 shows one example of a pattern of the voltage applied to
the liquid crystal molecule 10'. For example, the liquid crystal
molecule 10' is set to be homogeneously orientated (in a direction
parallel to a glass substrate face) in an initial state. In FIG.
18, the applied voltage is sequentially reduced in an order of
electrodes 11d and 11f, electrodes 11e and 11g, and electrodes 11b
and 11h around an electrode 11e as a center. The liquid crystal
molecule 10' is orientated in parallel with the glass substrate
face in a region for a weak electric field. However, the liquid
crystal molecule 10' is orientated in a region for a strong
electric field in a state in which the liquid crystal molecule is
inclined a certain angle with respect to the glass substrate face.
As a result, the refractive index distribution of an aggregation of
liquid crystal molecules 10' is changed as shown in FIG. 16 so that
converging characteristics similar to those of a cylindrical lens
are obtained. At this time, a changing width of the refractive
index of the aggregation of liquid crystal molecules 10' is
prescribed between maximum and minimum refractive indices peculiar
to the liquid crystal molecules 10'. A cylindrical lens array is
constructed by repeatedly providing such a pattern of the applied
voltage periodically in a horizontal direction.
When the pattern of the voltage applied to the electrode array 11
is changed, it is possible to control a distribution shape of the
refractive index of the aggregation of liquid crystal molecules
10', an entire level of the refractive index, and a pitch of the
refractive index distribution periodically repeated.
Optical characteristics of one cylindrical lens are prescribed by
three items composed of curvature of a cylindrical lens face, a
thickness of the cylindrical lens and a lens pitch. In the optical
characteristic variable lens shown in FIG. 15, the curvature of the
cylindrical lens face corresponds to a distribution shape of the
refractive index. The lens thickness corresponds to an entire level
of the refractive index. Further, the lens pitch corresponds to a
pitch of the refractive index distribution.
In this second embodiment shown in FIG. 15, similar to the
above-mentioned first embodiment shown in FIG. 12, it is possible
to cope with a three-dimensional image display corresponding to an
arbitrary number of parallax images. Further, an observation region
can be moved forward, backward, rightward and leftward by a remote
controller. In the first embodiment, this three-dimensional image
display is provided and the observation region can be moved by
changing a surface shape of the optical characteristic variable
lens. However, in the second embodiment, this three-dimensional
image display is provided and the observation region can be moved
by changing a refractive index distribution of the optical
characteristic variable lens. In this second embodiment, all
control operations of optical characteristics of the optical
characteristic variable lens can be electrically performed so that
no mechanical portion is required.
When the liquid crystal panel is used as a display element, it is
necessary to arrange two polarizing plates so that transmittance of
light is considerably reduced. However, no polarizing plates are
required in the optical characteristic variable lens in the present
invention so that no light amount is reduced.
In the above-mentioned optical characteristic variable lens, no
refractive index distribution is generated in a region in which no
voltage is applied to the optical characteristic variable lens.
Accordingly, no lens action is caused in this region. Therefore, a
normal two-dimensional image can be displayed in this region in
which no voltage is applied to the optical characteristic variable
lens. Accordingly, as shown in FIG. 14a, it is possible to display
two-dimensional and three-dimensional images in a state in which
these images are mixed with each other.
A strip-shaped electrode perpendicular to the electrode array 11
can be used instead of the entire face electrode 12 in FIG. 15. In
this case, as shown in FIG. 18, an arranging shape of this
strip-shaped electrode is equal to a arranging shape used for a
normal liquid crystal panel. In FIG. 18, driving circuits 43 and 44
are respectively connected to two sets of strip-shaped electrode
groups 41 and 42 perpendicular to each other. Operations of the
driving circuits 43 and 44 are controlled by a control circuit 45
such that a desirable voltage is applied to each of these
strip-shaped electrodes. Thus, images can be controlled in a
vertical direction (up-and-down direction) on the screen.
Accordingly, as shown in FIG. 14b, a three-dimensional image can be
displayed as a window within a two-dimensional image. Further, as
shown in FIG. 14c, a two-dimensional image can be displayed as a
window within a three-dimensional image. In this case, it is
necessary to scan the strip-shaped electrodes at a high speed.
However, when the above-mentioned perpendicular electrode
arrangement is used, the optical characteristic variable lens can
be used as a fly eye lens which also has a parallax in the vertical
direction.
In accordance with a first construction of the present invention, a
three-dimensional display unit comprises display means for
simultaneously displaying a plurality of different parallax images
and optical means attached to the display means and constructed by
an array of cylindrical lenses. Each of the cylindrical lenses is
formed such that a transparent substance having high flexibility is
supported by transparent electrodes from both substance sides and
optical characteristics of each of the cylindrical lenses can be
changed by applying a voltage to the transparent substance to
change at least one surface shape of the transparent substance.
Accordingly, no precise mechanical system is required when a space
for regenerating a stereoscopic image is moved. The
three-dimensional display unit has excellent responsibility and can
be made compact. Further, it is possible to cope with an arbitrary
three-dimensional image display from a two-eye type to a
multiple-eye type by changing a pattern of the applied voltage. An
observer can positively move the regenerating space of the
stereoscopic image by using a remote controller in an observation
distance direction in addition to a horizontal direction. Further,
no lens action is provided in a region in which no voltage is
applied to the transparent substance. Accordingly, the
three-dimensional display unit can be also used as a normal
two-dimensional image display unit. Therefore, it is possible to
display two-dimensional and three-dimensional images on the same
screen in a state in which these images are mixed with each other.
The stereoscopic image can be brightly and easily observed since
the three-dimensional display unit has no system for reducing a
light amount such as a liquid crystal parallax barrier system.
For example, the above optical characteristics include a focal
length.
In accordance with a seventh construction of the present invention,
a three-dimensional display unit comprises display means for
simultaneously displaying a plurality of different parallax images
and optical means attached to the display means and constructed by
an array of cylindrical lenses. Each of the cylindrical lenses is
formed such that a transparent substance having a refractive index
changed by a voltage applied to this transparent substance is
supported by transparent electrodes from both substance sides and
optical characteristics of each of the cylindrical lenses can be
changed by applying the voltage to the transparent substance to
provide a refractive index distribution for the transparent
substance.
Accordingly, a stereoscopic image is displayed by separating
parallax images from each other. At this time, a lens action is
caused by providing the refractive index distribution instead of a
change in shape of the optical means. Therefore, no structural
function of the three-dimensional display unit is easily reduced in
addition to the above effects of the three-dimensional display unit
having the first construction. Further, the optical means has a
flat surface so that it is possible to reduce influences of
irregular reflection of peripheral light, etc. causing problems at
an observation time.
In accordance with an eighth construction of the present invention,
the optical means is constructed by a liquid crystal in the
three-dimensional display unit. In this case, optical
characteristics of the liquid crystal can be greatly changed at a
smaller voltage.
In accordance with a ninth construction of the present invention,
the optical means acts as a two-dimensional lens array in the
three-dimensional display unit. In this case, perpendicular
strip-shaped electrode groups are used as the transparent
electrodes so that it is possible to display a stereoscopic image
having a parallax in a vertical direction in addition to a
horizontal direction.
FIG. 21 is a cross-sectional view showing the structure of a
three-dimensional display unit in accordance with another
embodiment of the present invention.
The three-dimensional display unit in this embodiment is of a
two-eye type in which an optical characteristic variable lens is
stuck to a flat display panel. The three-dimensional display unit
is constructed such that a space for regenerating a stereoscopic
image can be electrically controlled.
The three-dimensional display unit shown in FIG. 21 is constructed
by a liquid crystal panel 201 as a display means, an optical
characteristic variable lens 202 as an optical means, a head
detecting section 203 as a detecting means, and an optical
characteristic variable lens control section 204 as a control
means. The optical characteristic variable lens 202 is arranged
such that the optical characteristic variable lens 202 is closely
attached to the liquid crystal panel 201. The optical
characteristic variable lens control section 204 is connected to
the optical characteristic variable lens 202 and the head detecting
section 203.
Two different parallax images are displayed in the liquid crystal
panel 201 every other pixel. One portion of a parallax image
corresponding to a left-hand eye is displayed in a display pixel
D.sub.i1 of the liquid crystal panel 201. One portion of a parallax
image corresponding to a right-hand eye is displayed in a display
pixel D.sub.i2 of the liquid crystal panel 201. Index i is set to a
value from 1 to n.
These parallax images are similarly displayed on each of scanning
lines and one portions of the same parallax image are connected to
each other in a longitudinal direction of the liquid crystal panel.
When a color liquid crystal panel is used as the liquid crystal
panel 201, colors such as red, green and blue as one unit must be
arranged in the longitudinal direction. If no colors are arranged
in the longitudinal direction, image forming positions of
respective color pixels are separated from each other by a lens
action so that a shift in color is caused in a regenerated
image.
The liquid crystal panel 201 can be replaced with another flat
panel display. For example, the flat panel display can be
constructed by using an electroluminescence (EL) panel or a plasma
display.
The optical characteristic variable lens 202 is a lens having the
same converging action as a lenticular lens. Optical
characteristics of the optical characteristic variable lens 202 can
be electrically controlled. In this embodiment, the optical
characteristic variable lens 202 is constructed by an array of
cylindrical lenses L.sub.i.
FIG. 21 shows a cross section of a cylindrical lens L.sub.i. A
longitudinal direction of the cylindrical lens L.sub.i is in
conformity with a direction perpendicular to a paper face. Further,
the longitudinal direction of the cylindrical lens L.sub.i is set
to be in conformity with an array direction of pixels in which the
same parallax image is displayed in the liquid crystal panel 201.
The optical characteristic variable lens 202 will be described
later in detail.
The cylindrical lens L.sub.i within the optical characteristic
variable lens 202 corresponds to a pair of display pixels D.sub.i1
and D.sub.i2 within the liquid crystal panel 201. The cylindrical
lens L.sub.i is arranged such that the cylindrical lens is closely
attached to these display pixels. Light is transmitted through the
display pixels D.sub.i1 and D.sub.i2 and is separated into light
portions by a converging action of the cylindrical lens L.sub.i.
These light portions are projected into display spaces P and Q in
an observation region. Light is similarly separated and projected
with respect to all the display pixels from 1 to n. Thus, the
display space P for projecting the parallax image for the left-hand
eye and the display space Q for projecting the parallax image for
the right-hand eye are formed. An observer can observe a
stereoscopic image when the left-hand and right-hand eyes are
respectively located in the display spaces P and Q. Positions of
the display spaces P and Q can be controlled by changing the
relation in relative position between the display pixels D.sub.i1,
D.sub.i2 and the cylindrical lens L.sub.i.
The head detecting section 203 is arranged around the liquid
crystal panel 201. The head detecting section 203 detects the
spatial position of an observer's head and outputs position
information of the observer's head. The following detecting systems
are used in the head detecting section 203.
In a first detecting system, infrared ray emitting and receiving
elements are used as the head detecting section 203. In this first
detecting system, an infrared ray is emitted from the infrared ray
emitting element and is reflected on an observer's eye pupil. This
reflected infrared ray is received by the infrared ray receiving
element. Thus, a position of the observer's eye pupil is
detected.
In a second detecting system, an observer's face is photographed by
a video camera at any time. An observer's eye pupil is recognized
by processing an image of the observer's face so that a spatial
position of the observer's eye pupil is detected. In this second
detecting system, the head detecting section 203 is constructed by
the video camera, an image processing-recognizing device and a
position detector.
In a third detecting system, a magnetic field generator is attached
to an observer's head. A magnetic field is generated from this
magnetic field generator around the observer's head and is detected
by using a plurality of magnetic field detectors arranged on a
panel side so that a spatial position of the observer's head is
detected. In the third detecting system, the head detecting section
203 is constructed by the magnetic field generator, the plural
magnetic field detectors, a processor for processing signals from
the magnetic field detectors, etc. The magnetic field detectors may
be attached to the observer's head and the magnetic field generator
may be arranged on the panel side.
Position information of the observer's head detected by the head
detecting section 203 is transmitted to the optical characteristic
variable lens control section 204.
The optical characteristic variable lens control section 204
controls a refractive index and a refractive index distribution of
each of cylindrical lenses within the optical characteristic
variable lens 202 on the basis of the head position information
obtained by the head detecting section 203. Thus, an emitting
direction of light emitted from each of the cylindrical lenses is
changed so that the position of a space for regenerating a
stereoscopic image is controlled.
FIG. 15 explained above shows one constructional example of the
above optical characteristic variable lens. FIG. 16 shows the
refractive index distribution of an aggregation of liquid crystal
molecules 10'.
The relation between optical characteristics of a cylindrical lens
and the regenerating position of a stereoscopic image will next be
explained with reference to FIGS. 22 to 25.
FIG. 22 shows variables for determining the optical characteristics
of the cylindrical lens. The cylindrical lens L.sub.i corresponds
to central pixels D.sub.i1 and D.sub.i2 of a liquid crystal panel.
FIG. 15 shows a cross section of this cylindrical lens L.sub.i. The
cylindrical lens L.sub.i has a cylindrical face and a curvature
center of this cylindrical lens is set to an origin. A longitudinal
direction of the cylindrical face is set to a Y-axis. An arranging
direction of the cylindrical lens perpendicular to the Y-axis is
set to an X-axis. A Z-axis is perpendicular to the X-axis and the
Y-axis and is set to an axis extending in an observing
direction.
In the following description, reference numerals R and t
respectively designate a curvature radius of the cylindrical lens
face and a thickness of the cylindrical lens. Reference numerals P1
and n respectively designate a pitch of the cylindrical lens face
and a refractive index of the cylindrical lens. Further, reference
numeral Pd designates a width of each of display pixels D.sub.i1
and D.sub.i2 in the X-axis direction. Reference numeral PH
designates a shift in the X-axis direction between a middle point
of the display pixels D.sub.i1 and D.sub.i2 and a central axis of
the cylindrical lens L.sub.i as the Z-axis. Further, reference
numeral D designates a display pixel of the liquid crystal panel in
the X-axis direction.
An a-a' plane is set to a plane parallel to an X-Y plane in an
observation region and separated by a distance z.sub.0 from the X-Y
plane. Reference numeral d.sub.i designates a width of each of
images P and Q projected onto the a-a' plane in the X-axis
direction. Reference numeral x.sub.0 designates a distance between
the Z-axis and a middle point A of the projected images P and Q.
The width d.sub.i of each of the projected images is preferably set
to be equal to or wider than an average distance (about 65 mm)
between eye pupils of a man. However, when this width is set to an
excessively large value, light is dispersed so that the projected
images are darkened.
If an operation of the three-dimensional display unit is controlled
such that the point A is in conformity with a middle point of the
left-hand and right-hand eyes of an observer, the observer can see
a stereoscopic image even when the observer moves his head in a
certain moving range. Spatial positions (x.sub.0, z.sub.0) at the
point A can be controlled by adjusting the above variables t, R, Pl
and PH prescribing the optical characteristics of the cylindrical
lens. Pd, D, n and d.sub.i are set to fixed values in advance.
FIG. 23 shows the relation of an image projected from one display
pixel onto the a-a' plane. This image shows a simple similar figure
and satisfies the following formula (1).
In contrast to this, a lenticular lens is suitably focused on a
liquid crystal display face. A focusing condition of this
lenticular lens is satisfied by the following formula (2).
The lens thickness t and the curvature radius R of the cylindrical
face can be calculated as follows from the above formulas (1) and
(2).
In this case, t and R are calculated on the basis of the distance
z.sub.0 detected by the head position detecting section.
FIG. 24 shows the relation between the lens pitch P1 and a width
2Pd of two display pixels since the two-eye type is used. This lens
pitch P1 is set such that light transmitted through each of the
display pixels is concentrated to a regenerating space P or Q.
P1/2Pd is provided as follows.
In this formula (5), P1 is calculated as follows from the above
formulas (1) and (3) to (5).
FIG. 25 shows the relation between the position x.sub.0 of a
projected image and the shifting amount PH of a relative position
of a display pixel and the lenticular lens. This relation is
provided to control a spatial position at the central point A of a
projected pattern. PH/x.sub.0 is provided as follows.
PH is represented by the following formula (8) from the above
formulas (1) and (7).
Thus, the spatial position of the projected pattern at the point A
can be controlled if the curvature radius R of the cylindrical lens
face, the lens thickness t, the lens pitch P1, the relative shift
PH of the display pixel and the cylindrical lens at a central point
of the liquid crystal panel are controlled. The variables R, t, P1
and PH are calculated from the preset known width Pd of the display
pixel of the liquid crystal panel, the width d.sub.i of each of the
projected images P and Q projected onto the a-a' plane separated by
the distance z.sub.0 from the X-Y plane, the refractive index n of
the cylindrical lens, and the positions (x.sub.0, z.sub.0) of the
observer's head calculated by the head position detecting
section.
In the optical characteristic variable lens shown in FIG. 15, the
curvature radius R of the cylindrical lens face corresponds to the
shape of a refractive index distribution and is controlled by the
pattern shape of a voltage applied to the electrode array 11. The
lens thickness t corresponds to an entire level of the refractive
index distribution and is controlled by using an entire pattern
level of the voltage applied to the electrode array 11. The lens
pitch P1 corresponds to a periodically changing pitch of the
refractive index distribution and is controlled by using a pattern
pitch of the voltage applied to the electrode array 11. The
relative shift PH of the display pixel and the cylindrical lens at
the central point of the liquid crystal panel corresponds to a
periodically changing phase of the refractive index distribution
and can be controlled by shifting the pattern of the voltage
applied to the electrode array 11.
In this embodiment, all control operations of the optical
characteristics of the cylindrical lens can be electrically
performed so that no mechanical portion is required.
In the above-mentioned embodiment, the regenerating position of a
stereoscopic image is controlled in conformity with an observer's
position so that the stereoscopic image is observed in a wide
range. However, only two different parallax images are displayed in
the liquid crystal panel. Accordingly, no observed stereoscopic
image is moved even when the observer moves. Namely, in this
embodiment, the observation region is enlarged in the
three-dimensional display unit of the two-eye type.
When the observer's head is moved, it is natural to move the
observed stereoscopic image. Namely, it is desirable to provide a
three-dimensional display unit of a multiple-eye type having a
plurality of stereoscopic images. An embodiment corresponding to
the multiple-eye type will next be explained.
FIG. 28 shows the construction of a three-dimensional display unit
in accordance with another embodiment of the present invention.
The three-dimensional display unit shown in FIG. 26 is of a direct
viewing type in which a lenticular lens is arranged on the front
face of a liquid crystal panel. FIG. 26 particularly shows the case
of a four-eye type display.
The three-dimensional display unit shown in FIG. 26 is constructed
by a liquid crystal panel 201 as a display means, an optical
characteristic variable lens 202 as an optical means, a head
detecting section 203 as a detecting means, and an optical
characteristic variable lens control section 204 as a control
means. The three-dimensional display unit shown in FIG. 26 is also
constructed by a stereoscopic signal synthesizing section 242, a
stereoscopic signal selecting section 243 as a selecting means, and
stereoscopic signal sources 233 to 236. The optical characteristic
variable lens 202 is arranged such that the optical characteristic
variable lens 202 is closely attached onto a front face of the
liquid crystal panel 201. The optical characteristic variable lens
control section 204 is connected to the optical characteristic
variable lens 202 and the head detecting section 203. The
stereoscopic signal synthesizing section 242 is connected to the
liquid crystal panel 201. The stereoscopic signal selecting section
243 is connected to the stereoscopic signal synthesizing section
242. The stereoscopic signal sources 233 to 236 are connected to
the stereoscopic signal selecting section 243.
In the three-dimensional display unit shown in FIG. 26, the optical
characteristic variable lens 202 is stuck to the front face of the
liquid crystal panel 201. In the Peal three-dimensional display
unit, an illuminating light source for a display is arranged on a
rear face of the liquid crystal panel 201, but is omitted in FIG.
26.
In the embodiment shown in FIG. 26, the liquid crystal panel is
used as an image display panel. However, the three-dimensional
display unit can be constructed by using an electroluminescence
(EL) panel, a plasma display, a flat panel display of a light
emitting diode (LED) array, etc. In this case, no illuminating
light source for a display is required.
A color liquid crystal panel is normally used as the liquid crystal
panel 201. At this time, an arranging direction of a color filter
in the liquid crystal panel is set to be equal to a longitudinal
direction (vertical direction) of the lenticular lens so as not to
separate color images from each other by a lens action.
The optical characteristic variable lens 202 is constructed by an
array of cylindrical lenses. The optical characteristic variable
lens 202 shown in FIG. 26 shows a cross section of an array of
elongated cylindrical lenses extending in a direction perpendicular
to a paper face.
In the embodiment shown in FIG. 26, the three-dimensional display
unit is of a four-eye type in which four different parallax images
can be displayed. However, two different parallax images are
simultaneously displayed in this four-eye type. Accordingly, the
optical characteristic variable lens 202 used in this embodiment is
equal to that used in the three-dimensional display unit of the
normal two-eye type. Namely, a cylindrical lens L.sub.i within the
optical characteristic variable lens 202 is arranged such that this
cylindrical lens corresponds to a pair of display pixels D.sub.i1
and D.sub.i2. Index i is set to a value from 1 to n. Light is
transmitted through the display pixels D.sub.i1 and D.sub.i2 and is
separated into light portions in display spaces P and Q in an
observation region by a converging operation of the cylindrical
lens L.sub.i. When a parallax image for a left-hand eye is
displayed in the pixel D.sub.i1 and a parallax image for a
right-hand eye is displayed in the pixel D.sub.i2, an observer can
observe a stereoscopic image when the left-hand and right-hand eyes
are respectively located in the display spaces P and Q.
In FIG. 26, the cylindrical lens L.sub.i has the same shape.
However, a pitch of the pair of pixels D.sub.i1 and D.sub.i2 is
different from a pitch of the cylindrical lens L.sub.i. The pitch
of the cylindrical lens is set to be slightly smaller than the
pitch of the pair of pixels D.sub.i1 and D.sub.i2. Accordingly, a
center of the pixel pair is shifted from that of the corresponding
cylindrical lens in a peripheral portion of the liquid crystal
panel. An amount of this shift is increased as this shift is caused
in the peripheral portion of the liquid crystal panel. Incident
angles of the transmitted light incident to the cylindrical lens
from the respective pixels are different from each other by this
shift in central and peripheral portions of the liquid crystal
panel 201. Accordingly, the transmitted light from pixels in the
peripheral portion of the liquid crystal panel 201 can be converged
into the specified spaces P and Q in the observation region.
A means for obtaining parallax images displayed in the liquid
crystal panel 201 may be constructed by a photographing system
shown in FIG. 27. In this photographing system, for example, four
video cameras are spaced from each other at a constant interval
such that a central axis of each of the video cameras is directed
to a photographed object. Thus, four different images are obtained.
An image obtained by a camera 244 is set to an image 1 and is used
for the stereoscopic signal source 233 shown in FIG. 26. Similarly,
an image 2 obtained by a camera 245 is used for the stereoscopic
signal source 234. An image 3 obtained by a camera 246 is used for
the stereoscopic signal source 235. An image 4 obtained by a camera
247 is used for the stereoscopic signal source 236. A stereoscopic
image can be observed when the image of a left-hand side camera is
observed by a left-hand eye and the image of a right-hand side
camera is observed by a right-hand eye with respect to two adjacent
images of the above four images. In the four-eye type in this
embodiment, it is possible to observe stereoscopic images in three
different directions. The three different stereoscopic images are
observed by respectively seeing the images 1 and 2, the images 2
and 3, and the images 3 and 4 by the left-hand and right-hand eyes.
Computer graphics may be used as a means for generating four
different images. Each of the stereoscopic signal sources may be
operated in real time and stereoscopic signals of the stereoscopic
signal sources may be recorded to a signal storing system such as
an optical disk.
The head detecting section 203 is a device for detecting an
observer's head, especially, a spatial position at a middle point
of both eyes. There are some systems for detecting the observer's
head. In a first detecting system, the head detecting section has
an infrared ray emitting element and a near infrared ray is
irradiated to the observer's head. A position of the observer's
head is detected by measuring an intensity of the near infrared ray
reflected on the observer's head.
In a second detecting system, the observer is photographed by a
video camera or a charge coupled device (CCD) camera at any time.
Eye pupils of the observer are recognized by image processing so
that a spatial position of each of these eye pupils is detected. In
this case, the head detecting section includes the video camera, an
image processing-recognizing device and a position detector.
In a third detecting system, a magnetic field generator is attached
to the observer's head and a spatial position of the magnetic field
generator is detected by using a plurality of magnetic field
detectors. In this case, the head detecting section includes the
magnetic field generator, the plural magnetic field detectors, a
processor fop processing signals from the magnetic field detectors,
etc. In this third detecting system, the magnetic field detectors
may be attached to the observer's head and the magnetic field
generator may be arranged on a panel side.
A mechanical system, systems using supersonic waves and inertial
force, etc. may be used as another detecting system.
The next description relates to a technique for controlling the
regenerating position of a stereoscopic image in accordance with
the observer's head position and changing the regenerated
stereoscopic image.
When images are photographed and displayed by the photographing
system shown in FIG. 27, an observation region is partitioned in
advance by two planes perpendicular to the liquid crystal panel
201. Thus, the observation region is divided into three spaces S, T
and U (see FIG. 26) determined by a camera arrangement. The spaces
S and T are divided by a plane passing through a principal point of
a lens of the camera 245 and perpendicular to the liquid crystal
panel. The spaces T and U are divided by a plane passing through a
principal point of a lens of the camera 248 and perpendicular to
the liquid crystal panel.
Position information detected by the head detecting section 203 at
a middle point of both eyes is transmitted to the optical
characteristic variable lens control section 204. The optical
characteristic variable lens control section 204 controls the
positions of projected images P and Q displayed in a display pixel
D.sub.i1 or D.sub.i2 of the liquid crystal panel 201 by controlling
optical characteristics of the optical characteristic variable lens
202. The projecting positions of the projected images P and Q are
controlled such that a boundary point A of the projected images P
and Q is in conformity with the middle point of both the observer's
eyes.
A converging operation of the optical characteristic variable lens
202 is similar to that in the above-mentioned embodiment shown in
FIG. 21.
For example, four stereoscopic signal sources 233 to 236 obtained
by the above photographing system as shown in FIG. 27 are connected
to a stereoscopic signal selecting section 243. One of the four
stereoscopic signal sources is allocated to a signal for the
left-hand eye and another one of the four stereoscopic signal
sources is allocated to a signal for the right-hand eye by position
information of the observer's head. A stereoscopic signal
synthesizing section 242 divides two signals selected by the
stereoscopic signal selecting section 243 into signal portions in
even and odd fields. Parallax images for the left-hand and
right-hand eyes are displayed by the stereoscopic signal
synthesizing section 242 in the display pixels D.sub.i1 and
D.sub.i2 of the liquid crystal panel 201.
For example, when the middle point of both the observer's eyes is
located within the space T and the boundary point A (point A in
FIG. 26) is also located within the space T, an image 2 is
displayed in the display pixel D.sub.i1 of the liquid crystal panel
201 and an image 3 is displayed in the display pixel D.sub.i2 of
the liquid crystal panel 201. When the observer moves his head and
the boundary point A is moved into the space U by the movement of
the observer's head as shown by point A' in FIG. 26, the image 3 is
displayed in the display pixel D.sub.i1 of the liquid crystal panel
201 and an image 4 is displayed in the display pixel D.sub.i2 so
that the images are replaced.
Namely, images displayed in the liquid crystal panel 201 are
replaced in accordance with a space including the boundary point A
following the observer's position. The following Table 1 shows the
relation between a position of the boundary point A and a displayed
image.
TABLE 1 ______________________________________ position at point A
S T U display image number of D.sub.i1 1 2 3 display image number
of D.sub.i2 2 3 4 ______________________________________
The head position information detected by the head detecting
section 203 is also transmitted to the stereoscopic signal
selecting section 243. The stereoscopic signal selecting section
243 selects a combination of the stereoscopic signal sources shown
in the Table 1 on the basis of this head position information and
transmits a stereoscopic signal to the stereoscopic signal
synthesizing section 242.
A size of the space T depends on a distance between cameras of the
photographing system. Normally, the distance between the cameras is
preferably set to be in conformity with an average distance between
both eyes of a man. The distance between the cameras may be set to
be half or smaller than the average distance between both the eyes
so as to obtain a smoother change in images. In this case, if the
number of cameras is not increased, stereoscopic images are changed
so that an observable region is narrowed.
Thus, a stereoscopic image is regenerated in an optimum position in
conformity with the position of the observer's head even when the
observer moves his head. Further, the regenerated stereoscopic
image is moved in conformity with the position of the observer's
head. Accordingly, a very natural stereoscopic image can be
observed.
The present invention can be also applied to the three-dimensional
display unit of a projecting type. FIG. 28 is a cross-sectional
view showing a structure of the three-dimensional display unit of
the projecting type in another embodiment of the present
invention.
In the three-dimensional display unit of the projecting type shown
in FIG. 28, light is emitted from a light source 251 and is
converged by a condenser lens 253. The converged light is then
incident to a liquid crystal panel 201. This light is modulated by
the liquid crystal panel 201 and is transmitted through the liquid
crystal panel 201. The transmitted light is then focused and formed
by a projecting lens 252 as an image on a diffusive layer 250b
within an optical characteristic variable screen 250. Namely, an
image displayed in the liquid crystal panel 201 is enlarged and is
projected to the diffusive layer 250b.
The optical characteristic variable screen 250 is constructed by a
variable lenticular lens array 250a having optical characteristics
electrically controlled and,the diffusive layer 250b. The variable
lenticular lens array 250a has a structure shown in FIG. 15 or 13.
The optical characteristics of the variable lenticular lens array
205a are controlled by an optical characteristic variable screen
control section 254.
In the three-dimensional display unit of the projecting type, only
the projecting lens 252 and the diffusive layer 250b are arranged
between the variable lenticular lens array 250a and the liquid
crystal panel 201 in comparison with the direct viewing type.
Accordingly, there is no substantial difference between the
projecting type and the direct viewing type.
Accordingly, the above method for controlling the regenerating
position of a stereoscopic image and the above method for switching
display images are similarly applied to the three-dimensional
display unit of the projecting type. A head detecting section 203,
a stereoscopic signal synthesizing section 242, a stereoscopic
signal selecting section 243 and stereoscopic signal sources 233 to
236 have functions similar to those in the three-dimensional
display unit of the direct viewing type. Accordingly, operations of
these constructional sections and the stereoscopic signal sources
are similar to those in the three-dimensional display unit of the
direct viewing type.
In accordance with a fourteenth construction of the present
invention, a three-dimensional display unit comprises display means
for simultaneously displaying a plurality of different parallax
images; optical means attached to the display means and constructed
by an array of cylindrical lenses such that optical characteristics
of each of the cylindrical lenses can be changed; detecting means
for detecting a spatial position of an observer's head; and control
means connected to the detecting means and controlling an operation
of the optical means based on position information of the
observer's head detected by the detecting means such that a
stereoscopic image is regenerated in an optimum position of the
observer's head.
Accordingly, the spatial position of the observer's head is
detected by the detecting means so that an optimum projected image
can be displayed to the observer by controlling and setting a
regenerating position of the stereoscopic image to an optimum
position at any time. A lens having optical characteristics
electrically controlled is used as a means for controlling the
regenerating position of the stereoscopic image. Therefore, it is
not necessary to arrange a precise mechanical system and the
three-dimensional display unit has excellent responsibility and is
made compact. Further, the position of a controllable regenerating
space of the stereoscopic image can be also controlled in an
observing distance direction. Accordingly, a space movable in
accordance with a movement of the observer's head is set to a
three-dimensional space so that a degree of the observer's head
movement is increased.
In accordance with a nineteenth construction of the present
invention, a three-dimensional display unit comprises display means
for simultaneously displaying a plurality of different parallax
images; optical means attached to the display means and constructed
by an array of cylindrical lenses such that optical characteristics
of each of the cylindrical lenses can be changed; detecting means
for detecting a spatial position of an observer's head; control
means connected to the detecting means and controlling an operation
of the optical means based on position information of the
observer's head detected by the detecting means such that a
stereoscopic image is regenerated in an optimum position of the
observer's head; a plurality of stereoscopic signal sources for
performing a multiple-eye display; and selecting means connected to
the plural stereoscopic signal sources and the detecting means and
selecting a stereoscopic signal displayed to the display means on
the basis of the position information of the observer's head
detected by the detecting means.
Accordingly, the spatial position of the observer's head is
detected by the detecting means. A stereoscopic image display space
formed by a two-eye type lenticular lens is moved in accordance
with the detection of the spatial position. Further, the
regenerated image is selected by the selecting means connected to
the plural stereoscopic signal sources for performing a
multiple-eye display. Thus, a stereoscopic image according to the
observer's position is displayed. As a result, in addition of the
effects of the fourteenth construction, a stereoscopic image
changed smoothly and continuously can be displayed in conformity
with the observer's head position so that a very natural
stereoscopic image can be observed. Further, in addition to the
above effects, the screen of the three-dimensional display unit can
be large-sized by using a projector of a rear projecting type.
FIG. 29a is a cross-sectional view showing the construction of a
three-dimensional display unit in accordance with another
embodiment of the present invention. FIG. 29b is an enlarged view
of a main portion of the three-dimensional display unit shown in
FIG. 29a.
The three-dimensional display unit shown in FIG. 29a is of a direct
viewing type and a three-eye type in which a lenticular lens is
arranged on the front face of a liquid crystal panel.
The three-dimensional display unit shown in FIG. 29a has a liquid
crystal panel display 311, a comb type diffusive mask 312 and a
lenticular lens 313. The liquid crystal panel display 311
simultaneously displays a plurality of parallax images and emits
light from each of pixels. The comb type diffusive mask 312 is
attached to a surface of the liquid crystal panel display 311 and
has an elongated diffusive plate formed in a band shape. One
portion of light emitted from each of the pixels of the liquid
crystal panel display 311 is incident to the elongated diffusive
plate. An optical path of this incident light portion is changed by
the elongated diffusive plate and this light portion is emitted
from the elongated diffusive plate. The light portion emitted from
the comb type diffusive mask 312 is incident to the lenticular lens
313 and is emitted by the lenticular lens 313 to a non-display
space corresponding to a wiring portion of the liquid crystal panel
display 311.
In the real three-dimensional display unit, an illuminating light
source for a display is arranged on a rear face of the liquid
crystal panel 311, but is omitted in FIG. 29a.
In the embodiment shown in FIG. 29a, the liquid crystal panel is
used as an image display panel. The image display panel can be
constructed by using an electroluminescence (EL) panel, a plasma
display, a flat panel display of a light emitted diode (LED) array,
etc. In this case, no light source for a display is required.
A color liquid crystal panel is used as the liquid crystal panel
311. An arranging direction of a color filter in the liquid crystal
panel 311 is set to be equal to a longitudinal direction (vertical
direction) of the lenticular lens 313 so as not to separate color
images from each other by a converging action of the lenticular
lens.
The lenticular lens 313 is formed by an array of cylindrical
lenses. Each of FIGS. 29a and 29b shows a cross section of an array
of elongated cylindrical lenses extending in a direction
perpendicular to a paper face. The lenticular lens 313 is
constructed by a plastic material such as acrylic, vinyl chloride,
etc. The lenticular lens 313 is molded in a shape in which
cylindrical portions each having a preset radius of curvature are
arranged in a horizontal direction. A thickness of the lenticular
lens 313 is set such that the lenticular lens 313 is focused on the
liquid crystal panel 311.
The comb type diffusive mask 312 is constructed by small elongated
diffusive plates each having the same width as the wiring portion
of the liquid crystal panel 311 as a non-transmitting portion
through which no light is transmitted. The elongated diffusive
plates extend in the vertical direction and are arranged at the
same pitch as the display pixels of the liquid crystal panel
311.
The comb type diffusive mask 312 is constructed by elongated slits
each formed in a longitudinal stripe and arranged in the horizontal
direction. One unopen portion of the slits is formed as an
elongated diffusive plate and has the same width as the wiring
portion of the liquid crystal panel 311. This unopen portion as the
elongated diffusive plate is closely attached to the wiring portion
such that the unopen portion is arranged on a front face of the
wiring portion of the liquid crystal panel 311. The unopen portion
is constructed b F a material such as plastic, glass, transparent
ceramics, etc. It is preferable to set a thickness of the comb type
diffusive mask 312 to be thin as much as possible. However, when
the comb type diffusive mask 312 is excessively thin, no diffusive
effects of the comb type diffusive mask 312 are lost. The thickness
of the comb type diffusive mask 312 is determined by a diffusive
degree of the elongated diffusive plate.
The embodiment shown in FIG. 29a relates to the three-eye type in
which three different parallax images are displayed. One portion of
each of the parallax images is displayed in each of display pixels
D.sub.i1, D.sub.i2 and D.sub.i3 of the liquid crystal panel 311.
Index i is set to a value from 1 to n. A cylindrical lens L.sub.i
within the lenticular lens 313 corresponds to one set of display
pixels D.sub.i1, D.sub.i2 and D.sub.i3. The cylindrical lens
L.sub.i is arranged such that this cylindrical lens is closely
attached to the display pixels D.sub.i1, D.sub.i2 and Di3. Light is
transmitted through the display pixels D.sub.i1, D.sub.i2 and Di3
and is then transmitted through respective opening portions
S.sub.i1, S.sub.i2 and S.sub.i3 of the comb type diffusive mask
312. This light is separated and projected into each of display
spaces A, B and C in an observation region by a converging action
of the cylindrical lens L.sub.i.
Each of distances between centers of these spaces is set to an
average distance (about 65 mm) between man's eyes. For example, an
observer can observe a stereoscopic image when the left-hand and
right-hand eyes are respectively located in the spaces A and B.
One portion of the light transmitted through each of the display
pixels D.sub.i1, D.sub.i2 and D.sub.i3 is incident to each of
unopen portions M.sub.(i-1)3, M.sub.i1, M.sub.i2 and M.sub.i3 of
the comb type diffusive mask 312. Each of these unopen portions of
the comb type diffusive mask 312 is constructed by an elongated
diffusive plate. Light incident to this elongated diffusive plate
is ideally emitted in all directions. Accordingly, light emitted
from the elongated diffusive plates M.sub.i1 and Mi2 respectively
reaches spaces D and E, Namely, a non-display space in the general
example is set to a display space.
In this embodiment, a light intensity distribution on an
observation plane a-a' is provided as shown in FIG. 30 when the
observation plane a-a' is set within the observation region.
In FIG. 30, an overlapping region of two curves shows that lights
from two directions overlap each other. Therefore, an entire light
intensity is equal to a sum of light intensities in this
overlapping region. Accordingly, FIG. 30 shows that light having
intensity approximately equal to that in each of the spaces A, B
and C reaches each of the spaces D and E. In such a state, no
observer sees a black band as a non-display portion even when the
observer moves his head and an observed stereoscopic image is
changed from a combination of the spaces A and B to a combination
of the spaces B and C.
The light intensity distribution shown in FIG. 30 can be also
realized by changing a thickness and a curvature radius of the
lenticular lens 313. In this case, no black band is formed, but an
image is defocused.
FIG. 31 is a partially enlarged view of the three-dimensional
display unit in the embodiment shown in FIGS. 29a and 29b.
Elongated diffusive plates M.sub.i1 and M.sub.i2 are arranged in
front of wiring portions B.sub.i1 and B.sub.i2 of the liquid
crystal panel 311.
A three-dimensional display unit in accordance with another
embodiment of the present invention will next be described with
reference to each of FIGS. 32 to 34.
Each of FIGS. 32 to 34 enlarges one portion of each of a liquid
crystal panel and a comb type diffusive mask.
In FIG. 32, a transparent material such as glass, a plastic
material, etc. is used in a light transmitting portion in which no
elongated diffusive plate of a comb type diffusive mask 312 is
formed. The elongated diffusive plate can be held and the comb type
diffusive mask is easily molded as a whole by using the transparent
material in the light transmitting portion. If the transparent
material is set to be equal to the material of a lenticular lens
313, the above fourth object of the present invention can be
achieved by reducing a thickness of the lenticular lens 313
designed for the three-dimensional display unit by a thickness d of
the comb type diffusive mask 312. Accordingly, the lenticular lens
313 is easily designed.
Further, refractive indices of the comb type diffusive mask 312 and
the lenticular lens 313 are set to be equal to each other.
Accordingly, no light reflection is caused on a boundary face of
the comb type diffusive mask 312 and the lenticular lens 313 so
that light can be effectively utilized.
FIG. 33 shows a three-dimensional display unit in accordance with
another embodiment of the present invention.
In the three-dimensional display unit shown in FIG. 33, a diffusive
plate 314 having the same size as the screen size of a liquid
crystal panel 311 is arranged on a front face of the liquid crystal
panel 311 instead of the comb type diffusive mask.
In this embodiment, a stereoscopic image is defocused around a
stereoscopic observable region. However, this three-dimensional
display unit has a simplest structure for achieving an object of
the present invention in which no non-display space is caused
between display spaces. A thickness of the diffusive plate 314 is
determined by a diffusive degree of a material used for the
diffusive plate 314. In this case, a lenticular lens 313 is
designed such that the lenticular lens 313 is focused on a surface
of the diffusive plate 314.
FIG. 34 shows the construction of a three-dimensional display unit
in accordance with another embodiment of the present invention.
The three-dimensional display unit shown in FIG. 34 is constructed
such that a comb type diffusive mask is buried into a lenticular
lens 313.
The three-dimensional display unit shown in FIG. 34 is of a two-eye
type. A pitch of the lenticular lens 313 is set to be smaller than
the pitch of a display pixel D.sub.ij of a liquid crystal panel
311. However, the pitch of a buried elongated diffusive plate is
equal to the pitch of the display panel D.sub.ij of the liquid
crystal panel 311. Namely, the pitch of the lenticular lens 313 is
different from the pitch of the buried elongated diffusive
plate.
In the above-mentioned embodiments shown in FIG. 29 to 33, a
position of the comb type diffusive mask or the diffusive plate and
a position of the lenticular lens must be independently aligned
with respect to the liquid crystal panel. However, in this
embodiment shown in FIG. 34, it is sufficient to align the
lenticular lens with the liquid crystal panel.
FIG. 35a shows the construction of a three-dimensional display unit
in accordance with another embodiment of the present invention.
FIG. 35b is an enlarged view of one portion of the
three-dimensional display unit shown in FIG. 35a.
FIG. 35a shows a three-eye type. The three-dimensional display unit
of this three-eye type is constructed by a liquid crystal panel
321, a comb type diffusive mask 322 and a lenticular lens 323.
Different from the above-mentioned embodiments, a light
interrupting film C.sub.ij is arranged within an elongated
diffusive plate M.sub.ij (j=i, 2, 3) in the comb type diffusive
mask 322.
A function of the light interrupting film C.sub.ij will next be
explained.
As shown in FIG. 30, a black band can be removed from each of the
spaces D and E in the embodiment shown in FIG. 29a so that an
obstacle in movement of the observation region can be reduced.
However, light for each of the right-hand and left-hand eyes also
reaches each of the spaces D and E so that no correct stereoscopic
image can be seen in a hatching portion in FIG. 30.
As shown in FIG. 29a, this is because transmitted light on both
sides of an elongated diffusive plate is incident to this elongated
diffusive plate in the comb type diffusive mask 312. For example,
transmitted light from the display pixel D.sub.i1 and transmitted
light from the display pixel D.sub.i2 are incident to the elongated
diffusive plate M.sub.i1. These two transmitted lights are incident
to the elongated diffusive plate at separate incident angles, but
cannot be discriminated from each other when these lights are
emitted from the elongated diffusive plate.
Namely, as shown in FIG. 30, an image observed in the space D is
formed by mixing images observed in the spaces A and B with each
other so that no correct stereoscopic image can be seen.
In the embodiment shown in FIGS. 35a and 35b, the light
interrupting film C.sub.ij is arranged within the elongated
diffusive plate M.sub.ij so that the elongated diffusive plate
M.sub.ij is divided into two divisional portions M.sub.ijL and
M.sub.ijR.
FIG. 36 is a partially enlarged view of each of the liquid crystal
panel 321 and the comb type diffusive mask 322.
In FIG. 36, only transmitted light from a display pixel D.sub.i1 is
incident to the elongated diffusive plate M.sub.i1L and only
transmitted light from a display pixel D.sub.i2 is incident to the
elongated diffusive plate M.sub.i1R. Thus, light emitted from the
elongated diffusive plates is separated into light corresponding to
the transmitted light from the display pixel D.sub.i1 and light
corresponding to the transmitted light from the display pixel
D.sub.i2. Namely, an image portion observed in the space D and
located on the left-hand side of a dotted line is ideally equal to
an image observed in the space A. An image portion observed in the
space D and located on the right-hand side of the dotted line is
ideally equal to an image observed in the space B.
In this embodiment, when a certain observation plane a-a' is set
within an observation region, a light intensity distribution on
this observation plane a-a' is provided as shown in FIG.
A mixing region of images for the right-hand and left-hand eyes
shown by a hatching portion in FIG. 37 is greatly narrowed by a
light interrupting function of the light interrupting film C.sub.ij
in comparison with FIG. 30. Accordingly, it should be understood
that a stereoscopic observable space is widened until regions of
the spaces D and E.
The mixing region of images for the right-hand and left-hand eyes
shown by the hatching portion still exists in FIG. 37. However,
this mixing region is caused since an arc having an observing
distance as a radius around an observer as a center is approximated
by a straight line. To completely remove this mixing region, it is
sufficient to form the entire three-dimensional display unit in an
arc shape, or arrange the lenticular lens 323 or the liquid crystal
panel 321 at an irregular pitch. However, it is sufficient to
arrange only the comb type diffusive mask 322 to reduce an obstacle
in movement of the observation region.
The construction of the three-dimensional display unit shown in
FIGS. 35 to 37 can be also applied to the above embodiment shown in
each of FIGS. 31 to 34. Namely, features of the three-dimensional
display unit in each of these embodiments can be provided by
arranging a light interrupting film formed by a diffusive material
in a portion corresponding to a wiring portion of the liquid
crystal panel. As a result, a black band can be removed from an
image without defocusing this image.
As mentioned above, in the three-dimensional display unit of the
present invention, a plurality of parallax images are displayed in
a mixing state in a flat panel display every one pixel. One set of
plural pixels correspond to one cylindrical lens constituting a
lenticular lens. Thus, lights emitted from the respective pixels
are separated from each other so that a projecting pattern of each
of the parallax images is formed. At this time, one portion of
light emitted from each of the pixels is incident to a diffusive
plate formed in a band shape and arranged on the front face of a
vertical wiring portion as a non-transmitting portion in the above
flat panel display.
The above diffusive plate having the band shape is arranged on each
of front faces of all vertical wiring portions as non-transmitting
portions in the above flat panel display. Accordingly, the entire
diffusive plate has the same pitch as the pixels of the flat panel
display and is formed as a comb type diffusive mask having an
unopen portion (diffusive plate) of a comb type.
An optical path of light incident to the diffusive plate is changed
by the diffusive plate. Accordingly, in an observation region,
light emitted from the diffusive plate reaches a space to which no
light from a pixel can be transmitted when no diffusive plate is
arranged. Thus, it is possible to reduce a non-display space
corresponding to the wiring portion of the flat panel display.
Accordingly, no observer sees a black band as an obstacle in
stereoscopic observation when an observing position is moved.
In the three-dimensional display unit of the present invention, an
opening portion of the above comb type diffusive mask is
constructed by a transparent material so that the structure of the
three-dimensional display unit is maintained and the
three-dimensional display unit is easily molded.
When a refractive index of the above transparent material is set to
be equal to the refractive index of a lenticular lens, a thickness
of the lenticular lens is reduced by a thickness of the comb type
diffusive mask. Thus, with respect to the emitted light not
incident to the diffusive plate from the pixel of the flat panel
display, it is possible to realize the same converging state as a
case in which no comb type diffusive mask is arranged.
In another three-dimensional display unit of the present invention,
plural parallax images are displayed in a mixing state every one
pixel in the flat panel display. A diffusive plate is arranged on a
front face of the flat panel display along an entire screen.
Further, a lenticular lens is arranged on a front face of the
diffusive plate. At this time, one set of plural pixels correspond
to one cylindrical lens constituting the lenticular lens. Thus,
lights emitted from the respective pixels are separated from each
other so that a projecting pattern of each of the parallax images
is formed.
An image on the above flat panel display is once projected onto the
diffusive plate arranged between the flat panel display and the
lenticular lens. A boundary between a certain pixel and an adjacent
pixel becomes indefinite with respect to the projected image on the
diffusive plate. Therefore, when the projecting pattern of each of
the parallax images is formed, a boundary of lights separated by
the lenticular lens also becomes indefinite. Accordingly, no
observer sees a black band as an obstacle in stereoscopic
observation when an observing position is moved.
The three-dimensional display unit of the present invention has an
integral structure in which the above comb type diffusive mask and
the lenticular lens are integrated with each other. Namely, when
the lenticular lens is molded, the diffusive plate molded in a band
shape in advance is buried onto a contact face side of the
lenticular lens coming in contact with the flat panel display at
the same pitch as a pitch of display pixels of the flat panel
display. Otherwise, a diffusive substance is injected onto this
contact face side such that the diffusive plate is formed in a band
shape. Thus, the integral structure is obtained. An optical path of
light emitted from the lenticular lens is equal to that in the
above-mentioned three-dimensional display unit.
When the comb type diffusive mask and the lenticular lens have
separate structures, it is necessary to independently align
positions of the flat panel display and the comb type diffusive
mask, and positions of the comb type diffusive mask and the
lenticular lens. These aligning operations are easily performed by
setting the flat panel display, the comb type diffusive mask and
the lenticular lens to an integral structure.
Further, in the three-dimensional display unit of the present
invention, a light interrupting film is inserted into the diffusive
plate formed in a band shape and constituting the above comb type
diffusive mask. The diffusive plate formed in a band shape is
arranged at the same pitch as the pixel pitch of the flat panel
display. Accordingly, the light interrupting film is also arranged
at the same pitch as the pixel pitch of the flat panel display. One
diffusive plate formed in a band shape is separated into two plate
portions by this light interrupting film. In an observation region,
light emitted from the diffusive plate reaches a space to which no
light from a pixel is transmitted when no diffusive plate is
arranged. This emitted light reaches this space by the lenticular
lens. Thus, a non-display space corresponding to a wiring portion
of the flat panel display is reduced. At this time, since the
diffusive plate is separated into the two plate portions, incident
light for a left-hand eye from a right-hand side of the diffusive
plate is converged onto a left-hand side of this space. Further,
incident light fop a right-hand eye from a left-hand side of the
diffusive plate is converged onto a right-hand side of this space.
Accordingly, the incident lights for the left-hand and right-hand
eyes are separately converged onto the left-hand and right-hand
sides of this space. Namely, the lenticular lens makes light reach
a space to which no light from a display pixel is transmitted when
no masking means is arranged. Further, lights emitted from adjacent
display pixels are allocated to different spaces by the lenticular
lens.
Accordingly, no observer sees a black band as an obstacle in
stereoscopic observation when an observing position is moved.
Further, a stereoscopic observable region is enlarged in a
horizontal direction. Namely, effects equivalent to reduction of
the wiring portion of the flat panel display in size in the
horizontal direction and enlargement of a display pixel portion in
the horizontal direction can be obtained by arranging the light
interrupting film within the diffusive plate.
Further, in the three-dimensional display unit of the present
invention, the light interrupting film is inserted into the
diffusive plate and is arranged at the same pitch as the pixel
pitch of the flat panel display. Features of the above
three-dimensional display unit can be added by this inserted light
interrupting film.
In accordance with a third construction of the present invention, a
three-dimensional display unit comprises display means having a
plurality of pixels and a non-transmitting portion and
simultaneously displaying a plurality of parallax images and
emitting light from each of the pixels; masking means attached to a
surface of the display means and arranged at the same pitch as a
pitch of the respective pixels in accordance with the
non-transmitting portion of the display means; the masking means
having an unopen portion constructed such that one portion of light
emitted from each of the pixels is incident to the unopen portion
and is emitted from the unopen portion by changing an optical path
of the incident light by the unopen portion; and lens means
constructed by an array of cylindrical lenses each having the same
shape and attached to a surface of the masking means. Accordingly,
the size of a non-display space can be reduced so that no observer
sees a black band as an obstacle in stereoscopic observation when
an observing position is moved.
In accordance with a fourth construction of the present invention,
the unopen portion of the masking means has a light interrupting
film for reducing the size of a non-display space corresponding to
the non-transmitting portion of the display means. Accordingly, the
unopen portion is divided into two portions so that lights incident
to the unopen portion from two different pixels can be separated
from each other when these lights are emitted from the unopen
portion. Thus, it is possible to enlarge an observation region for
a stereoscopic image.
FIG. 38a is a plan view showing the structure of a liquid crystal
panel 401 as a display means used in a three-dimensional display
unit of the present invention. FIG. 38b is a plan view showing the
structure of a lenticular lens 402 as an optical means. In FIGS.
38a and 38b, the three-dimensional display unit is of a two-eye
type as one example.
FIG. 38a shows a display state of the liquid crystal panel 401 at a
certain time for a vertical scanning period. In FIG. 38a, a main
scanning line provided by applying a voltage having a positive
polarity to the liquid crystal panel 401 is shown by a solid line.
A main scanning line provided by applying a voltage having a
negative polarity to the liquid crystal panel 401 is shown by a
dotted line. One portion of an image for a right-hand eye is
displayed by first, third, fifth, - - - , main scanning lines. One
portion of an image for a left-hand eye is displayed by second,
fourth, sixth, - - - , main scanning lines.
In the following description, the number of parallax images
displayed in the liquid crystal panel is set to N showing an N-eye
type. In this case, one portion of a certain parallax image is
displayed in the liquid crystal panel 401 every N-main scanning
lines. One portion of another parallax image is also displayed
every N-main scanning lines adjacent to the previous main scanning
lines. Thus, N-parallax images are cut and are sequentially
connected and are simultaneously displayed in the liquid crystal
panel.
The following first explanation relates to a three-dimensional
display unit of a direct viewing type in which the lenticular lens
is directly stuck to a display face of the liquid crystal
panel.
FIG. 39 is a cross-sectional view showing the structure of a
three-dimensional display unit of a two-eye type in a lenticular
system of a direct viewing type.
One portion of a parallax image corresponding to a left-hand eye is
displayed in a display pixel D.sub.i1 of a liquid crystal panel
401. One portion of a parallax image corresponding to a right-hand
eye is displayed in a display pixel D.sub.i2 of the liquid crystal
panel 401. A cylindrical lens L.sub.i is arranged such that the
cylindrical lens corresponds to a pair of display pixels D.sub.i1
and D.sub.i2.
Light is transmitted through the display pixels D.sub.i1 and
D.sub.2 and is separated into light portions in display spaces P
and Q within an observation region by a converging action of the
cylindrical lens L.sub.i. Light is similarly separated into light
portions in the display spaces P and Q with respect to each of
values of index i from 1 to n. Thus, the parallax image for the
left-hand eye is converged into the display space P and the
parallax image for the right-hand eye is converged into the display
space Q. A stereoscopic image can be observed when the left-hand
and right-hand eyes are respectively located in the display spaces
P and Q.
The lenticular lens 402 is constructed by an array of cylindrical
lenses. The lenticular lens 402 is normally formed by a plastic
material such as acrylic, vinyl chloride, etc.
The liquid crystal panel 401 is arranged in a longitudinal position
such that a main scanning line is in conformity with a longitudinal
direction of each of the cylindrical lenses within the lenticular
lens 402.
When information of different parallax images is displayed every
main scanning line, signal processing is simplified since it is
sufficient to switch signal sources every main scanning line.
Therefore, information of different parallax images is displayed
every main scanning line in many cases.
The next description relates to a case in which the number N of
parallax images is set to an even number. In this embodiment,
polarities of a voltage applied to the liquid crystal panel on a
main scanning line are inverted every N-parallax images.
Since the three-dimensional display unit shown in FIGS. 38a and 38b
is of the two-eye type, one cylindrical lens corresponds to two
main scanning lines. In the case of an N-eye type, one cylindrical
lens corresponds to N-main scanning lines.
FIG. 40 shows a polarity inverting system in this embodiment. In
the case of the N-eye type such as the two-eye type, polarities of
the applied voltage are inverted every N-main scanning lines such
as two main scanning lines. In a certain vertical scanning period
(frame), first and second main scanning lines show a positive
polarity. Third and fourth main scanning lines show a negative
polarity. Fifth and sixth main scanning lines show the positive
polarity. Seventh and eighth main scanning lines show the negative
polarity. The driving voltage is applied to the liquid crystal
panel in such a polarity inverting order. Further, in the next
vertical scanning period, the driving voltage having a polarity
inverse to that provided in the vertical scanning period just
before the next vertical scanning period is applied to the liquid
crystal panel on the same main scanning line. Namely, the first and
second main scanning lines show a negative polarity. The third and
fourth main scanning lines show a positive polarity. The fifth and
sixth main scanning lines show the negative polarity. The seventh
and eighth main scanning lines show the positive polarity. The
driving voltage is applied to the liquid crystal panel in such a
polarity inverting order.
FIGS. 41a and 41b respectively show images for left-hand and
right-hand eyes in the display state shown in FIGS. 38a and 38b in
which these images are separated and projected by the converging
action of the lenticular lens 402. Similar to FIGS. 38a and 38b, a
main scanning line with respect to the applied voltage having a
positive polarity is shown by a solid line. A main scanning line
with respect to the applied voltage having a negative polarity is
shown by a dotted line.
As shown in FIGS. 40 and 41, main scanning lines provided by
different polarities are alternately mixed with each other within
one image with respect to the images for the left-hand and
right-hand eyes. Accordingly, one image is not constructed by main
scanning lines provided by the same polarity. With respect to a
change with the passage of time, polarities of the applied voltage
on each of the main scanning lines are inverted every one vertical
scanning period so that no voltage having the same polarity is
applied to the liquid crystal panel at any time.
In this embodiment, a phase on a main scanning line for
periodically displaying a parallax image in accordance with the
cylindrical lens may not be necessarily in conformity with a phase
for periodically inverting the polarities of the applied voltage on
the main scanning line.
The three-eye type will next be explained as one example in which
the number N of parallax images showing the N-eye type is set to an
odd number.
FIG. 42a shows a display state of a liquid crystal panel 401 at a
certain time for a vertical scanning period. A main scanning line
provided by a positive polarity is shown by a solid line. A main
scanning line provided by a negative polarity is shown by a dotted
line. One portion of a parallax image C is displayed on first,
fourth, seventh, - - - , main scanning lines. One portion of a
parallax image B is displayed on second, fifth, eighth, - - - ,
main scanning lines. One portion of a parallax image A is displayed
on third, sixth, ninth, - - - , main scanning lines. FIG. 42b is a
cross-sectional view of a lenticular lens 402 arranged on a front
face of the liquid crystal panel 401. Since the three-dimensional
display unit shown in FIGS. 42a and 42b is of the three-eye type,
one cylindrical lens corresponds to three main scanning lines.
FIG. 43 shows a polarity inverting pattern when the number N of
parallax images is set to an odd number. Polarities of the applied
voltage are inverted every one main scanning line. In a certain
vertical scanning period (frame), the driving voltage is applied to
the liquid crystal panel such that first, third, fifth, - - - ,
main scanning lines show a positive polarity and second, fourth,
sixth, - - - , main scanning lines show a negative polarity. In the
next vertical scanning period, the driving voltage having a
polarity inverse to that provided in the vertical scanning period
just before the next vertical scanning period is applied to the
liquid crystal panel on the same main scanning line. Namely, the
driving voltage is applied to the liquid crystal panel such that
the first, third, fifth, - - - , main scanning lines show the
negative polarity and the second, fourth, sixth, - - - , main
scanning lines show the positive polarity.
FIGS. 44a, 44b and 44c respectively show parallax images A, B and C
in the display state shown in FIGS. 42a and 42b in which the
parallax images are separated and projected by a converging action
of the lenticular lens 402. Similar to FIGS. 42a and 42b, a main
scanning line provided by a positive polarity is shown by a solid
line and a main scanning line provided by a negative polarity is
shown by a dotted line.
As shown in FIGS. 43 and 44, main scanning lines provided by
different polarities are alternately mixed with each other within
one image with respect to the parallax images A, B and C.
Accordingly, one image is not constructed by main scanning lines
provided by the same polarity. With respect to a change with the
passage of time, polarities of the applied voltage on each of the
main scanning lines are inverted every one vertical scanning period
so that no voltage having the same polarity is applied to the
liquid crystal panel at any time.
Similar effects can be obtained by inverting the polarities of the
applied voltage every other main scanning line even when the number
of parallax images is equal to an odd number except for 3.
When the number N of parallax images is set to an odd number,
similar to the above case of the even number, similar effects can
be also obtained by inverting the polarities of the applied voltage
every N-main scanning lines.
The present invention can be also applied to a three-dimensional
display unit of a projecting type.
FIG. 45 is a cross-sectional view showing a structure of the
three-dimensional display unit of the projecting type.
In the three-dimensional display unit of the projecting type shown
in FIG. 45, light is emitted from a light source 421 and is
converged by a condenser lens 425. The converged light is incident
to a liquid crystal panel 401. The incident light is modulated by
the liquid crystal panel 401 and is transmitted through this liquid
crystal panel 401. The transmitted light is then focused and formed
by a projecting lens 422 as an image on a diffusive layer 420b
within a lenticular screen 420. Thus, an image displayed in the
liquid crystal panel 401 is enlarged and projected to the diffusive
layer 420b of the lenticular screen 420.
The lenticular screen 420 is constructed by an array 420a of
cylindrical lenses and the diffusive layer 420b.
In the projecting type, only the projecting lens 422 is inserted
between the liquid crystal panel 401 and the lenticular lens 420 in
comparison with the directing viewing type. Accordingly, there is
no substantial difference between the projecting type and the
direct viewing type with respect to a basic function of the
three-dimensional display unit.
Similar to the direct viewing type, when the liquid crystal panel
401 is arranged in a longitudinal position in the projecting type
and the number N of parallax images is set to an even number, the
polarities of an applied voltage are inverted every N-main scanning
lines. In contrast to this, when the number N of parallax images is
set to an odd number, the polarities of the applied voltage are
inverted every one main scanning line or every N-main scanning
lines. Thus, effects similar to those obtained by the direct
viewing type can be obtained.
As mentioned above, in the three-dimensional display unit of the
present invention, each of plural parallax images reproduced and
projected in a stereoscopic observation space are constructed by
alternately mixing main scanning lines provided by an applied
voltage having different polarities. Accordingly, one image is not
constructed by main scanning lines provided by the same polarity.
Namely, an image is averaged in space and time even when the
applied voltage is slightly changed by a difference between voltage
polarities and a difference in brightness between images is caused
by this polarity difference. Accordingly, no flicker phenomenon is
caused and no difference in brightness between parallax images
incident to right-hand and left-hand eyes is caused. Further, the
voltage polarities on one main scanning line are inverted every
vertical scanning period (frame). Accordingly, electrolysis of
liquid crystal molecules can be restrained so that life of a liquid
crystal panel can be increased.
In accordance with a fifth construction of the present invention, a
three-dimensional display unit comprises display means for
simultaneously displaying a predetermined number of different
parallax images, and optical means constructed by an array of
cylindrical lenses such that a longitudinal direction of each of
the cylindrical lenses is equal to a vertical direction. The
display means scans a main scanning line thereof in the vertical
direction such that this main scanning line is in conformity with
the longitudinal direction of each of the cylindrical lenses. The
polarities of a voltage applied to the display means are inverted
on the main scanning line every predetermined number of parallax
images. The voltage having a polarity inverse to that in the
previous frame is repeatedly applied to the display means in the
next frame every main scanning line. Accordingly, it is possible to
provide a three-dimensional display unit with high quality and
reduced fatigue.
In accordance with a sixth construction of the present invention,
the display means inverts the voltage polarities every one main
scanning line when the number of different parallax images is equal
to an odd number. The voltage having a polarity inverse to that in
the previous frame is repeatedly applied to the display means in
the next frame every main scanning line. Accordingly, it is
possible to provide a three-dimensional display unit with high
quality and reduced fatigue.
Many widely different embodiments of the present invention may be
constructed without departing from the spirit and scope of the
present invention. It should be understood that the present
invention is not limited to the specific embodiments described in
the specification, except as defined in the appended claims.
* * * * *